A ZIP Code is a postal code used by the United States Postal Service in a system it introduced in 1963. The term ZIP is an acronym for Zone Improvement Plan; the basic format consists of five digits. An extended ZIP+4 code was introduced in 1983 which includes the five digits of the ZIP Code, followed by a hyphen and four additional digits that reference a more specific location; the term ZIP Code was registered as a servicemark by the U. S. Postal Service, but its registration has since expired; the early history and context of postal codes began with postal district/zone numbers. The United States Post Office Department implemented postal zones for numerous large cities in 1943. For example: The "16" was the number of the postal zone in the specific city. By the early 1960s, a more organized system was needed, non-mandatory five-digit ZIP Codes were introduced nationwide on July 1, 1963; the USPOD issued its Publication 59: Abbreviations for Use with ZIP Code on October 1, 1963, with the list of two-letter state abbreviations which are written with both letters capitalized.
An earlier list in June had proposed capitalized abbreviations ranging from two to five letters. According to Publication 59, the two-letter standard was "based on a maximum 23-position line, because this has been found to be the most universally acceptable line capacity basis for major addressing systems", which would be exceeded by a long city name combined with a multi-letter state abbreviation, such as "Sacramento, Calif." along with the ZIP Code. The abbreviations have remained unchanged, with the exception of Nebraska, changed from NB to NE in 1969 at the request of the Canadian postal administration, to avoid confusion with the Canadian province of New Brunswick. Robert Moon is considered the father of the ZIP Code; the post office only credits Moon with the first three digits of the ZIP Code, which describe the sectional center facility or "sec center." An SCF is a central mail processing facility with those three digits. The fourth and fifth digits, which give a more precise locale within the SCF, were proposed by Henry Bentley Hahn Sr.
The SCF sorts mail to all post offices with those first three digits in their ZIP Codes. The mail is sorted according to the final two digits of the ZIP Code and sent to the corresponding post offices in the early morning. Sectional centers do not deliver mail and are not open to the public, most of their employees work the night shift. Mail picked up at post offices is sent to their own SCF in the afternoon, where the mail is sorted overnight. In the case of large cities, the last two digits coincide with the older postal zone number thus: In 1967, these became mandatory for second- and third-class bulk mailers, the system was soon adopted generally; the United States Post Office used a cartoon character, which it called Mr. ZIP, to promote the use of the ZIP Code, he was depicted with a legend such as "USE ZIP CODE" in the selvage of panes of postage stamps or on the covers of booklet panes of stamps. In 1971 Elmira Star-Gazette reporter Dick Baumbach found out the White House was not using a ZIP Code on its envelopes.
Herb Klein, special assistant to President Nixon, responded by saying the next printing of envelopes would include the ZIP Code. In 1983, the U. S. Postal Service introduced an expanded ZIP Code system that it called ZIP+4 called "plus-four codes", "add-on codes", or "add-ons". A ZIP+4 Code uses the basic five-digit code plus four additional digits to identify a geographic segment within the five-digit delivery area, such as a city block, a group of apartments, an individual high-volume receiver of mail, a post office box, or any other unit that could use an extra identifier to aid in efficient mail sorting and delivery. However, initial attempts to promote universal use of the new format met with public resistance and today the plus-four code is not required. In general, mail is read by a multiline optical character reader that instantly determines the correct ZIP+4 Code from the address—along with the more specific delivery point—and sprays an Intelligent Mail barcode on the face of the mail piece that corresponds to 11 digits—nine for the ZIP+4 Code and two for the delivery point.
For Post Office Boxes, the general rule is. The add-on code is one of the following: the last four digits of the box number, zero plus the last three digits of the box number, or, if the box number consists of fewer than four digits, enough zeros are attached to the front of the box number to produce a four-digit number. However, there is no uniform rule, so the ZIP+4 Code must be looked up individually for each box; the ZIP Code is translated into an Intelligent Mail barcode, printed on the mailpiece to make it easier for automated machines to sort. A barcode can be printed by the sender, it is better to let the post office put one on. In general, the post office uses OCR technology, though in some cases a human might have to read and enter the address. Customers who send bulk mail can get a discount on postage if they have printed the barcode themselves and have presorted the mai
American Community Survey
The American Community Survey is an ongoing survey by the U. S. Census Bureau, it gathers information contained only in the long form of the decennial census, such as ancestry, educational attainment, language proficiency, disability and housing characteristics. These data are used by many public-sector, private-sector, not-for-profit stakeholders to allocate funding, track shifting demographics, plan for emergencies, learn about local communities. Sent to 295,000 addresses monthly, it is the largest household survey that the Census Bureau administers; the United States Constitution requires an enumeration of the population every ten years and “in such Manner as they shall by Law direct.” From the first census in 1790, legislators understood that the census should collect basic demographic information beyond the number of people in the household. James Madison first proposed including questions in the census to “enable them to adapt the public measures to the particular circumstances of the community.”
Such knowledge collected with each census, he said, “would give them an opportunity of marking the progress of the society." The number and type of questions included in censuses since 1790 have reflected current American societal trends and the growing nation’s expanded data needs. By 1940, advancements in statistical methods enabled the Census Bureau to start asking a sample of the population a subset of additional detailed questions without unduly increasing cost or respondent burden. In subsequent decades, questions, asked of all respondents, as well as new questions, moved to the subsample questionnaire form; as that form grew longer than the census form sent to most households, it became known as the census “long form.” Following the 1960 Census, federal and local government officials, as well as those working in the private sector, began demanding more timely long-form-type data. Lawmakers representing rural districts claimed they were at a data disadvantage, unable to self-fund additional surveys of their populations.
Congress explored the creation of a mid-decade census, holding hearings and authorizing a mid-decade census in 1976, but not funding it. Efforts to obtain data on a more frequent basis began again after the 1990 Census, when it became clear that the more burdensome long form was depressing overall census response rates and jeopardizing the accuracy of the count. At Congress's request, the Census Bureau tested a new design to obtain long-form data. U. S. statistician Leslie Kish had introduced the concept of a rolling sample design in 1981. This design featured ongoing, monthly data collection aggregated on a yearly basis, enabling annual data releases. By combining multiple years of this data, the Census Bureau could release "period" estimates to produce estimates for smaller areas. After a decade of testing, it launched as the American Community Survey in 2005, replacing the once-a-decade census long form; the ACS has an initial sample of 3.5 million housing unit addresses and group quarters in the United States.
The Census Bureau selects a random sample of addresses to be included in the ACS. Each address has about a 1-in-480 chance of being selected in a given month, no address should be selected more than once every five years. Data is collected by internet, telephone interviews and in-person interviews. One third of those who do not respond to the survey by mail or telephone are randomly selected for in-person interviews. About 95 percent of households across all response modes respond. Like the decennial census, ACS responses are confidential; every employee at the Census Bureau takes an oath of nondisclosure and is sworn for life to not disclose identifying information. Violations can result in a 5-year prison sentence and/or $250,000 fine. Under 13 U. S. C. § 9, census responses are "immune from legal process" and may not "be admitted as evidence or used for any purpose in any action, suit, or other judicial or administrative proceeding." The Census Bureau aggregates individual ACS responses into estimates at many geographic summary levels.
Among these summary levels are legal and administrative entities such as states, counties and congressional districts, as well as statistical entities such as metropolitan statistical areas, block groups, census designated places. Estimates for census blocks are not available from ACS. In order to balance geographic resolution, temporal frequency, statistical significance, respondent privacy, ACS estimates released each year are aggregated from responses received in the previous calendar year or previous five calendar years; the Census Bureau provides guidance for data users about which data set to use when analyzing different population and geography sizes. From 2007 to 2013, 3-year estimates were available for areas with 20,000 people or more; this data product was discontinued in 2015 due to budget cuts. The last 3-year release was the 2011-2013 ACS 3-year estimates. Current data releases include: 1-year estimates are available for areas with a population of at least 65,000 people; the 2015 ACS 1-year estimates were released in 2016 and summarize responses received in 2015 for all states but only 26% of counties due to the 65,000 minimum population threshold.
This is most suitable for data users interested in shorter-term changes at medium to large geographic scales. Supplemental estimates are shown in annual tables summarizing populations for geographies with populations of 20,000 or more. 5-year estimates are available for areas down to the block group scale, on the order of 600 to 3000 people. The 2015 ACS 5-yea
Marriage called matrimony or wedlock, is a or ritually recognised union between spouses that establishes rights and obligations between those spouses, as well as between them and any resulting biological or adopted children and affinity. The definition of marriage varies around the world not only between cultures and between religions, but throughout the history of any given culture and religion, evolving to both expand and constrict in who and what is encompassed, but it is principally an institution in which interpersonal relationships sexual, are acknowledged or sanctioned. In some cultures, marriage is recommended or considered to be compulsory before pursuing any sexual activity; when defined broadly, marriage is considered a cultural universal. A marriage ceremony is known as a wedding. Individuals may marry for several reasons, including legal, libidinal, financial and religious purposes. Whom they marry may be influenced by gender determined rules of incest, prescriptive marriage rules, parental choice and individual desire.
In some areas of the world, arranged marriage, child marriage and sometimes forced marriage, may be practiced as a cultural tradition. Conversely, such practices may be outlawed and penalized in parts of the world out of concerns of the infringement of women's rights, or the infringement of children's rights, because of international law. Around the world in developed democracies, there has been a general trend towards ensuring equal rights within marriage for women and recognizing the marriages of interfaith and same-sex couples; these trends coincide with the broader human rights movement. Marriage can be recognized by a state, an organization, a religious authority, a tribal group, a local community, or peers, it is viewed as a contract. When a marriage is performed and carried out by a government institution in accordance with the marriage laws of the jurisdiction, without religious content, it is a civil marriage. Civil marriage recognizes and creates the rights and obligations intrinsic to matrimony before the state.
When a marriage is performed with religious content under the auspices of a religious institution it is a religious marriage. Religious marriage recognizes and creates the rights and obligations intrinsic to matrimony before that religion. Religious marriage is known variously as sacramental marriage in Catholicism, nikah in Islam, nissuin in Judaism, various other names in other faith traditions, each with their own constraints as to what constitutes, who can enter into, a valid religious marriage; some countries do not recognize locally performed religious marriage on its own, require a separate civil marriage for official purposes. Conversely, civil marriage does not exist in some countries governed by a religious legal system, such as Saudi Arabia, where marriages contracted abroad might not be recognized if they were contracted contrary to Saudi interpretations of Islamic religious law. In countries governed by a mixed secular-religious legal system, such as in Lebanon and Israel, locally performed civil marriage does not exist within the country, preventing interfaith and various other marriages contradicting religious laws from being entered into in the country, civil marriages performed abroad are recognized by the state if they conflict with religious laws.
The act of marriage creates normative or legal obligations between the individuals involved, any offspring they may produce or adopt. In terms of legal recognition, most sovereign states and other jurisdictions limit marriage to opposite-sex couples and a diminishing number of these permit polygyny, child marriages, forced marriages. In modern times, a growing number of countries developed democracies, have lifted bans on and have established legal recognition for the marriages of interfaith and same-sex couples; some cultures allow the dissolution of marriage through annulment. In some areas, child marriages and polygamy may occur in spite of national laws against the practice. Since the late twentieth century, major social changes in Western countries have led to changes in the demographics of marriage, with the age of first marriage increasing, fewer people marrying, more couples choosing to cohabit rather than marry. For example, the number of marriages in Europe decreased by 30% from 1975 to 2005.
In most cultures, married women had few rights of their own, being considered, along with the family's children, the property of the husband. In Europe, the United States, other places in the developed world, beginning in the late 19th century and lasting through the 21st century, marriage has undergone gradual legal changes, aimed at improving the rights of the wife; these changes included giving wives legal identities of their own, abolishing the right of husbands to physically discipline their wives, giving wives property rights, liberalizing divorce laws, providing wives with reproductive rights of their own, requiring a wife's consent when sexual relations occur. These changes have occurred in Western countries. In the 21st century, there continue to be controversies regarding the legal status of married women, legal acceptance of or leniency towards violence within marriage, traditional marriage customs such as dowry and bride price, for
Illinois is a state in the Midwestern and Great Lakes region of the United States. It has the fifth largest gross domestic product, the sixth largest population, the 25th largest land area of all U. S. states. Illinois is noted as a microcosm of the entire United States. With Chicago in northeastern Illinois, small industrial cities and immense agricultural productivity in the north and center of the state, natural resources such as coal and petroleum in the south, Illinois has a diverse economic base, is a major transportation hub. Chicagoland, Chicago's metropolitan area, encompasses over 65% of the state's population; the Port of Chicago connects the state to international ports via two main routes: from the Great Lakes, via the Saint Lawrence Seaway, to the Atlantic Ocean and from the Great Lakes to the Mississippi River, via the Illinois Waterway to the Illinois River. The Mississippi River, the Ohio River, the Wabash River form parts of the boundaries of Illinois. For decades, Chicago's O'Hare International Airport has been ranked as one of the world's busiest airports.
Illinois has long had a reputation as a bellwether both in social and cultural terms and, through the 1980s, in politics. The capital of Illinois is Springfield, located in the central part of the state. Although today's Illinois' largest population center is in its northeast, the state's European population grew first in the west as the French settled the vast Mississippi of the Illinois Country of New France. Following the American Revolutionary War, American settlers began arriving from Kentucky in the 1780s via the Ohio River, the population grew from south to north. In 1818, Illinois achieved statehood. Following increased commercial activity in the Great Lakes after the construction of the Erie Canal, Chicago was founded in the 1830s on the banks of the Chicago River at one of the few natural harbors on the southern section of Lake Michigan. John Deere's invention of the self-scouring steel plow turned Illinois's rich prairie into some of the world's most productive and valuable farmland, attracting immigrant farmers from Germany and Sweden.
The Illinois and Michigan Canal made transportation between the Great Lakes and the Mississippi River valley faster and cheaper, new railroads carried immigrants to new homes in the country's west and shipped commodity crops to the nation's east. The state became a transportation hub for the nation. By 1900, the growth of industrial jobs in the northern cities and coal mining in the central and southern areas attracted immigrants from Eastern and Southern Europe. Illinois was an important manufacturing center during both world wars; the Great Migration from the South established a large community of African Americans in the state, including Chicago, who founded the city's famous jazz and blues cultures. Chicago, the center of the Chicago Metropolitan Area, is now recognized as a global alpha-level city. Three U. S. presidents have been elected while living in Illinois: Abraham Lincoln, Ulysses S. Grant, Barack Obama. Additionally, Ronald Reagan, whose political career was based in California, was born and raised in the state.
Today, Illinois honors Lincoln with its official state slogan Land of Lincoln, displayed on its license plates since 1954. The state is the site of the Abraham Lincoln Presidential Library and Museum in Springfield and the future home of the Barack Obama Presidential Center in Chicago. "Illinois" is the modern spelling for the early French Catholic missionaries and explorers' name for the Illinois Native Americans, a name, spelled in many different ways in the early records. American scholars thought the name "Illinois" meant "man" or "men" in the Miami-Illinois language, with the original iliniwek transformed via French into Illinois; this etymology is not supported by the Illinois language, as the word for "man" is ireniwa, plural of "man" is ireniwaki. The name Illiniwek has been said to mean "tribe of superior men", a false etymology; the name "Illinois" derives from the Miami-Illinois verb irenwe·wa - "he speaks the regular way". This was taken into the Ojibwe language in the Ottawa dialect, modified into ilinwe·.
The French borrowed these forms, changing the /we/ ending to spell it as -ois, a transliteration for its pronunciation in French of that time. The current spelling form, began to appear in the early 1670s, when French colonists had settled in the western area; the Illinois's name for themselves, as attested in all three of the French missionary-period dictionaries of Illinois, was Inoka, of unknown meaning and unrelated to the other terms. American Indians of successive cultures lived along the waterways of the Illinois area for thousands of years before the arrival of Europeans; the Koster Site demonstrates 7,000 years of continuous habitation. Cahokia, the largest regional chiefdom and urban center of the Pre-Columbian Mississippian culture, was located near present-day Collinsville, Illinois, they built an urban complex of more than 100 platform and burial mounds, a 50-acre plaza larger than 35 football fields, a woodhenge of sacred cedar, all in a planned design expressing the culture's cosmology.
Monks Mound, the center of the site, is the largest Pre-Columbian structure north of the Valley of Mexico. It is 100 feet high, 951 feet long, 836 feet wide, covers 13.8 acres. It contains about 814,000 cubic yards of earth, it was topped by a structure thought to have measured about 105 feet in length and 48 feet in width, covered an area 5,000 square feet, been as much as 50 feet high, making its peak 150 feet above the level of the pl
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
A census is the procedure of systematically acquiring and recording information about the members of a given population. The term is used in connection with national population and housing censuses; the United Nations defines the essential features of population and housing censuses as "individual enumeration, universality within a defined territory and defined periodicity", recommends that population censuses be taken at least every 10 years. United Nations recommendations cover census topics to be collected, official definitions and other useful information to co-ordinate international practice; the word is of Latin origin: during the Roman Republic, the census was a list that kept track of all adult males fit for military service. The modern census is essential to international comparisons of any kind of statistics, censuses collect data on many attributes of a population, not just how many people there are. Censuses began as the only method of collecting national demographic data, are now part of a larger system of different surveys.
Although population estimates remain an important function of a census, including the geographic distribution of the population, statistics can be produced about combinations of attributes e.g. education by age and sex in different regions. Current administrative data systems allow for other approaches to enumeration with the same level of detail but raise concerns about privacy and the possibility of biasing estimates. A census can be contrasted with sampling in which information is obtained only from a subset of a population. Modern census data are used for research, business marketing, planning, as a baseline for designing sample surveys by providing a sampling frame such as an address register. Census counts are necessary to adjust samples to be representative of a population by weighting them as is common in opinion polling. Stratification requires knowledge of the relative sizes of different population strata which can be derived from census enumerations. In some countries, the census provides the official counts used to apportion the number of elected representatives to regions.
In many cases, a chosen random sample can provide more accurate information than attempts to get a population census. A census is construed as the opposite of a sample as its intent is to count everyone in a population rather than a fraction. However, population censuses rely on a sampling frame to count the population; this is the only way to be sure that everyone has been included as otherwise those not responding would not be followed up on and individuals could be missed. The fundamental premise of a census is that the population is not known and a new estimate is to be made by the analysis of primary data; the use of a sampling frame is counterintuitive as it suggests that the population size is known. However, a census is used to collect attribute data on the individuals in the nation; this process of sampling marks the difference between historical census, a house to house process or the product of an imperial decree, the modern statistical project. The sampling frame used by census is always an address register.
Thus it is not known how many people there are in each household. Depending on the mode of enumeration, a form is sent to the householder, an enumerator calls, or administrative records for the dwelling are accessed; as a preliminary to the dispatch of forms, census workers will check any address problems on the ground. While it may seem straightforward to use the postal service file for this purpose, this can be out of date and some dwellings may contain a number of independent households. A particular problem is what are termed'communal establishments' which category includes student residences, religious orders, homes for the elderly, people in prisons etc; as these are not enumerated by a single householder, they are treated differently and visited by special teams of census workers to ensure they are classified appropriately. Individuals are counted within households and information is collected about the household structure and the housing. For this reason international documents refer to censuses of housing.
The census response is made by a household, indicating details of individuals resident there. An important aspect of census enumerations is determining which individuals can be counted from which cannot be counted. Broadly, three definitions can be used: de facto residence; this is important to consider individuals who have temporary addresses. Every person should be identified uniquely as resident in one place but where they happen to be on Census Day, their de facto residence, may not be the best place to count them. Where an individual uses services may be more useful and this is at their usual, or de jure, residence. An individual may be represented at a permanent address a family home for students or long term migrants, it is necessary to have a precise definition of residence to decide whether visitors to a country should be included in the population count. This is becoming more important as students travel abroad for education for a period of several years. Other groups causing problems of enumeration are new born babies, people away on holiday, people moving home around census day, people without a fixed address.
People having second homes because of working in another part of the country or retaining a holiday cottage are dif
Population density is a measurement of population per unit area or unit volume. It is applied to living organisms, most of the time to humans, it is a key geographical term. In simple terms population density refers to the number of people living in an area per kilometer square. Population density is population divided by total land water volume, as appropriate. Low densities may lead to further reduced fertility; this is called the Allee effect after the scientist. Examples of the causes in low population densities include: Increased problems with locating sexual mates Increased inbreeding For humans, population density is the number of people per unit of area quoted per square kilometer or square mile; this may be calculated for a county, country, another territory or the entire world. The world's population is around 7,500,000,000 and Earth's total area is 510,000,000 square kilometers. Therefore, the worldwide human population density is around 7,500,000,000 ÷ 510,000,000 = 14.7 per km2. If only the Earth's land area of 150,000,000 km2 is taken into account human population density is 50 per km2.
This includes all continental and island land area, including Antarctica. If Antarctica is excluded population density rises to over 55 people per km2. However, over half of the Earth's land mass consists of areas inhospitable to human habitation, such as deserts and high mountains, population tends to cluster around seaports and fresh-water sources. Thus, this number by itself does not give any helpful measurement of human population density. Several of the most densely populated territories in the world are city-states and dependencies; these territories have a small area and a high urbanization level, with an economically specialized city population drawing on rural resources outside the area, illustrating the difference between high population density and overpopulation The potential to maintain the agricultural aspects of deserts is limited as there is not enough precipitation to support a sustainable land. The population in these areas are low. Therefore, cities in the Middle East, such as Dubai, have been increasing in population and infrastructure growth at a fast pace.
Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources. Most of the most densely populated cities are in Southeast Asia, though Cairo and Lagos in Africa fall into this category. City population and area are, however dependent on the definition of "urban area" used: densities are invariably higher for the central city area than when suburban settlements and the intervening rural areas are included, as in the areas of agglomeration or metropolitan area, the latter sometimes including neighboring cities. For instance, Milwaukee has a greater population density when just the inner city is measured, the surrounding suburbs excluded. In comparison, based on a world population of seven billion, the world's inhabitants, as a loose crowd taking up ten square feet per person, would occupy a space a little larger than Delaware's land area; the Gaza Strip has a population density of 5,046 pop/km.
Although arithmetic density is the most common way of measuring population density, several other methods have been developed to provide a more accurate measure of population density over a specific area. Arithmetic density: The total number of people / area of land Physiological density: The total population / area of arable land Agricultural density: The total rural population / area of arable land Residential density: The number of people living in an urban area / area of residential land Urban density: The number of people inhabiting an urban area / total area of urban land Ecological optimum: The density of population that can be supported by the natural resources Demography Human geography Idealized population Optimum population Population genetics Population health Population momentum Population pyramid Rural transport problem Small population size Distance sampling List of population concern organizations List of countries by population density List of cities by population density List of city districts by population density List of English districts by population density List of European cities proper by population density List of United States cities by population density List of islands by population density List of U.
S. states by population density List of Australian suburbs by population density Selected Current and Historic City, Ward & Neighborhood Density Duncan Smith / UCL Centre for Advanced Spatial Analysis. "World Population Density". Exploratory map shows data from the Global Human Settlement Layer produced by the European Commission JRC and the CIESIN Columbia University