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
Keith County, Nebraska
Keith County is a county in the U. S. state of Nebraska. As of the 2010 United States Census, the population was 8,368, its county seat is Ogallala. In the Nebraska license plate system, Keith County is represented by the prefix 68. Keith County was formed in 1873. Sources differ on the Keith after whom it was named: either M. C. Keith of North Platte, whose grandson Keith Neville became Nebraska's 18th governor in 1917; the terrain of Keith County consists of low rolling hills. The level areas are used for agriculture in the lower part of the county; the North Platte River flows eastward into the northwest end of the county, feeding Lake McConaughy exiting the county's east line near its midpoint. The South Platte River flows eastward into the southwest end of the county, crosses the lower central part of the county before exiting to the east, headed for its junction with the North Platte River well to the east of Keith County; the county has an area of 1,110 square miles, of which 1,062 square miles is land and 48 square miles is water.
Most of Nebraska's 93 counties observe Central Time. Keith County is the easternmost of the Nebraska counties to observe Mountain Time. Clear Creek State Waterfowl Management Area Lake McConaughy State Recreation Area As of the census of 2000, there were 8,875 people, 3,707 households, 2,535 families residing in the county; the population density was 8 people per square mile. There were 5,178 housing units at an average density of 5 per square mile; the racial makeup of the county was 96.75% White, 0.08% Black or African American, 0.71% Native American, 0.17% Asian, 1.49% from other races, 0.80% from two or more races. 4.23% of the population were Hispanic or Latino of any race. There were 3,707 households out of which 30.20% had children under the age of 18 living with them, 58.60% were married couples living together, 7.00% had a female householder with no husband present, 31.60% were non-families. 27.90% of all households were made up of individuals and 13.50% had someone living alone, 65 years of age or older.
The average household size was 2.37 and the average family size was 2.89. In the county, the population was spread out with 25.30% under the age of 18, 5.70% from 18 to 24, 25.30% from 25 to 44, 25.40% from 45 to 64, 18.40% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 96.50 males. For every 100 females age 18 and over, there were 92.80 males. The median income for a household in the county was $32,325, the median income for a family was $39,118. Males had a median income of $26,523 versus $19,024 for females; the per capita income for the county was $17,421. About 6.60% of families and 9.30% of the population were below the poverty line, including 13.10% of those under age 18 and 8.20% of those age 65 or over. Ogallala Brule Paxton Belmar Keystone Lemoyne Martin RoscoeSarben Nevens Ruthton Bertha Korty Megeath Oren Pickard Plano National Register of Historic Places listings in Keith County, NebraskaJohn Janovy Jr. "Keith County Journal" St. Martin's Press John Janovy Jr. "Yellowlegs: A Migration of the Mind" Houghton Mifflin Company John Janovy Jr.
"Back in Keith County" University of Nebraska Press
Per capita income
Per capita income or average income measures the average income earned per person in a given area in a specified year. It is calculated by dividing the area's total income by its total population. Per capita income is national income divided by population size. Per capita income is used to measure an area's average income and compare the wealth of different populations. Per capita income is used to measure a country's standard of living, it is expressed in terms of a used international currency such as the euro or United States dollar, is useful because it is known, is calculable from available gross domestic product and population estimates, produces a useful statistic for comparison of wealth between sovereign territories. This helps to ascertain a country's development status, it is one of the three measures for calculating the Human Development Index of a country. In the United States, it is defined by the U. S. Census Bureau as the following: "Per capita income is the mean money income received in the past 12 months computed for every man and child in a geographic area."
Critics claim that per capita income has several weaknesses in measuring prosperity: Comparisons of per capita income over time need to consider inflation. Without adjusting for inflation, figures tend to overstate the effects of economic growth. International comparisons can be distorted by cost of living differences not reflected in exchange rates. Where the objective is to compare living standards between countries, adjusting for differences in purchasing power parity will more reflect what people are able to buy with their money, it does not reflect income distribution. If a country's income distribution is skewed, a small wealthy class can increase per capita income while the majority of the population has no change in income. In this respect, median income is more useful when measuring of prosperity than per capita income, as it is less influenced by outliers. Non-monetary activity, such as barter or services provided within the family, is not counted; the importance of these services varies among economies.
Per capita income does not consider whether income is invested in factors to improve the area's development, such as health, education, or infrastructure. List of countries by average wage List of countries by GDP per capita—GDP at market or government official exchange rates per inhabitant List of countries by GDP per capita—GDP calculated at purchasing power parity exchange per inhabitant List of countries by GNI per capita List of countries by GNI per capita List of countries by income equality Total personal income
1910 United States Census
The Thirteenth United States Census, conducted by the Census Bureau on April 15, 1910, determined the resident population of the United States to be 92,228,496, an increase of 21.0 percent over the 76,212,168 persons enumerated during the 1900 Census. The 1910 Census switched from a portrait page orientation to a landscape orientation; the 1910 census collected the following information: Full documentation for the 1910 census, including census forms and enumerator instructions, is available from the Integrated Public Use Microdata Series. The column titles in the census form are as follows: LOCATION. Street, road, etc. House number. 1. Number of dwelling house in order of visitation. 2. Number of family in order of visitation. 3. NAME of each person whose place of abode on April 15, 1910, was in this family. Enter surname first the given name and middle initial, if any. Include every person living on April 15, 1910. Omit children born since April 15, 1910. RELATION. 4. Relationship of this person to the head of the family.
PERSONAL DESCRIPTION. 5. Sex. 6. Color or race. 7. Age at last birthday. 8. Whether single, widowed, or divorced. 9. Number of years of present marriage. 10. Mother of how many children: Number born. 11. Mother of how many children: Number now living. NATIVITY. Place of birth of each person and parents of each person enumerated. If born in the United States, give the state or territory. If of foreign birth, give the country. 12. Place of birth of this Person. 13. Place of birth of Father of this person. 14. Place of birth of Mother of this person. CITIZENSHIP. 15. Year of immigration to the United States. 16. Whether naturalized or alien. 17. Whether able to speak English. OCCUPATION. 18. Trade or profession of, or particular kind of work done by this person, as spinner, laborer, etc. 19. General nature of industry, business, or establishment in which this person works, as cotton mill, dry goods store, etc. 20. Whether as employer, employee, or work on own account. If an employee— 21. Whether out of work on April 15, 1910.
22. Number of weeks out of work during year 1909. EDUCATION. 23. Whether able to read. 24. Whether able to write. 25. Attended school any time since September 1, 1909. OWNERSHIP OF HOME. 26. Owned or rented. 27. Owned free or mortgaged. 28. Farm or house. 29. Number of farm schedule. 30. Whether a survivor of the Union or Confederate Army or Navy. 31. Whether blind. 32. Whether deaf and dumb. Special Notation In 1912 and 1959, New Mexico, Arizona and Hawaii would become the 47th, 48th, 49th and 50th states admitted to the Union; the 1910 population count for each of these areas was 327,301, 204,354, 64,356 and 191,909 respectively. On this basis, the ranking list above would be modified as follows: First 42 ranked states - positions unchanged New Mexico, Arizona, Hawaii, Wyoming and Alaska; the original census enumeration sheets were microfilmed by the Census Bureau in the 1940s. The microfilmed census is available in rolls from the National Records Administration. Several organizations host images of the microfilmed census online, along which digital indices.
Microdata from the 1910 census are available through the Integrated Public Use Microdata Series. Aggregate data for small areas, together with electronic boundary files, can be downloaded from the National Historical Geographic Information System. 1911 U. S Census Report Contains 1910 Census results Historic US Census data census.gov/population/www/censusdata/PopulationofStatesandCountiesoftheUnitedStates1790-1990.pdf
1890 United States Census
The Eleventh United States Census was taken beginning June 2, 1890. It determined the resident population of the United States to be 62,979,766—an increase of 25.5 percent over the 50,189,209 persons enumerated during the 1880 census. The data was tabulated by machine for the first time; the data reported that the distribution of the population had resulted in the disappearance of the American frontier. Most of the 1890 census materials were destroyed in a 1921 fire and fragments of the US census population schedule exist only for the states of Alabama, Illinois, New Jersey, New York, North Carolina, South Dakota, Texas, the District of Columbia; this was the first census in which a majority of states recorded populations of over one million, as well as the first in which multiple cities – New York as of 1880, Philadelphia – recorded populations of over one million. The census saw Chicago rank as the nation's second-most populous city, a position it would hold until 1990, in which Los Angeles would supplant it.
The 1890 census collected the following information: The 1890 census was the first to be compiled using methods invented by Herman Hollerith and was overseen by Superintendents Robert P. Porter and Carroll D. Wright. Data was entered on a machine readable medium, punched cards, tabulated by machine; the net effect of the many changes from the 1880 census: the larger population, the number of data items to be collected, the Census Bureau headcount, the volume of scheduled publications, the use of Hollerith's electromechanical tabulators, was to reduce the time required to process the census from eight years for the 1880 census to six years for the 1890 census. The total population of 62,947,714, the family, or rough, was announced after only six weeks of processing; the public reaction to this tabulation was disbelief, as it was believed that the "right answer" was at least 75,000,000. The United States census of 1890 showed a total of 248,253 Native Americans living in the United States, down from 400,764 Native Americans identified in the census of 1850.
The 1890 census announced that the frontier region of the United States no longer existed, that the Census Bureau would no longer track the westward migration of the U. S. population. Up to and including the 1880 census, the country had a frontier of settlement. By 1890, isolated bodies of settlement had broken into the unsettled area to the extent that there was hardly a frontier line; this prompted Frederick Jackson Turner to develop his Frontier Thesis. The original data for the 1890 Census is no longer available. All the population schedules were damaged in a fire in the basement of the Commerce Building in Washington, D. C. in 1921. Some 25 % of the materials were presumed another 50 % damaged by smoke and water; the damage to the records led to an outcry for a permanent National Archives. In December 1932, following standard federal record-keeping procedures, the Chief Clerk of the Bureau of the Census sent the Librarian of Congress a list of papers to be destroyed, including the original 1890 census schedules.
The Librarian was asked by the Bureau to identify any records which should be retained for historical purposes, but the Librarian did not accept the census records. Congress authorized destruction of that list of records on February 21, 1933, the surviving original 1890 census records were destroyed by government order by 1934 or 1935; the other censuses for which some information has been lost are the 1810 enumerations. Few sets of microdata from the 1890 census survive, but aggregate data for small areas, together with compatible cartographic boundary files, can be downloaded from the National Historical Geographic Information System. Mayo-Smith, Richmond, "The Eleventh Census of the United States". In: The Economic Journal, Vol. 1, p. 43 - 58 1891 U. S Census Report Contains 1890 Census results Historical US Census data from the U. S. Census Bureau website Hollerith 1890 Census Tabulator by Columbia University "The Fate of the 1890 Population Census" from the National Archives website
1940 United States Census
The Sixteenth United States Census, conducted by the Census Bureau, determined the resident population of the United States to be 132,164,569, an increase of 7.3 percent over the 1930 population of 123,202,624 people. The census date of record was April 1, 1940. A number of new questions were asked including where people were 5 years before, highest educational grade achieved, information about wages; this census introduced sampling techniques. Other innovations included a field test of the census in 1939; this was the first census in which every state had a population greater than 100,000. The 1940 census collected the following information: In addition, a sample of individuals were asked additional questions covering age at first marriage and other topics. Full documentation on the 1940 census, including census forms and a procedural history, is available from the Integrated Public Use Microdata Series. Following completion of the census, the original enumeration sheets were microfilmed; as required by Title 13 of the U.
S. Code, access to identifiable information from census records was restricted for 72 years. Non-personally identifiable information Microdata from the 1940 census is available through the Integrated Public Use Microdata Series. Aggregate data for small areas, together with electronic boundary files, can be downloaded from the National Historical Geographic Information System. On April 2, 2012—72 years after the census was taken—microfilmed images of the 1940 census enumeration sheets were released to the public by the National Archives and Records Administration; the records are indexed only by enumeration district upon initial release. Official 1940 census website 1940 Census Records from the U. S. National Archives and Records Administration 1940 Federal Population Census Videos, training videos for enumerators at the U. S. National Archives Selected Historical Decennial Census Population and Housing Counts from the U. S. Census Bureau Snow, Michael S. "Why the huge interest in the 1940 Census?"
CNN. Monday April 9, 2012. 1941 U. S Census Report Contains 1940 Census results 1940 Census Questions Hosted at CensusFinder.com
Center pivot irrigation
Center-pivot irrigation called water-wheel and circle irrigation, is a method of crop irrigation in which equipment rotates around a pivot and crops are watered with sprinklers. A circular area centered on the pivot is irrigated creating a circular pattern in crops when viewed from above. Most center pivots were water-powered, today most are propelled by electric motors. Center-pivot irrigation was invented in 1940 by farmer Frank Zybach, who lived in Strasburg, Colorado, it is recognized as an effective method to improve water distribution to fields. In 1952, Zybach went into business with a friend from Columbus, Nebraska. Trowbridge got 49 % of the patent rights. Zybach moved back from Colorado to Columbus, opened a shop, hired a few men, moved the height of the pipe up to six feet, went into business. In the first two years of operation, they sold only 19 systems; the early designs were finicky and few farmers understood the systems. Zybach kept improving his designs and focused on making his machines better, rather than attempting to sell systems with problems.
Zybach saw success with modified designs. In 1954, he licensed his patent to his company, Valley Manufacturing. Daugherty's engineers spent the next decade refining Zybach's innovation – making it sturdier and more reliable – and converting it from a hydraulic power system to electric drive. Daugherty's company went on to grow into Valmont Industries, with its subsidiary Valley Irrigation continuing his vision for irrigation in the United States spanning the globe. Center pivot irrigation is a form of overhead sprinkler irrigation consisting of several segments of pipe with sprinklers positioned along their length, joined together and supported by trusses, mounted on wheeled towers; the machine moves in a circular pattern and is fed with water from the pivot point at the center of the circle. For a center pivot to be used, the terrain needs to be reasonably flat; this advantage has resulted in water use in some areas. The system is in use, for example, in parts of the United States, New Zealand, Brazil and in desert areas such as the Sahara and the Middle East.
Center pivots are less than 1600 feet in length with the most common size being the standard 1/4 mile machine. A typical 1/4 mile radius crop circle covers about 125 acres of land Originally, most center pivots were water-powered; these were replaced by electric motor-driven systems. Most systems today are driven by an electric motor mounted at each tower; the outside set of wheels sets the master pace for the rotation. The inner sets of wheels are mounted at hubs between two segments and use angle sensors to detect when the bend at the joint exceeds a certain threshold; when the angle is too large, the wheels rotate to keep the segments aligned. To achieve uniform application, center pivots require an emitter flow rate across the radius of the machine. Since the outer-most spans travel farther in a given time period than the innermost spans, nozzle sizes are smallest at the inner spans and increase with distance from the pivot point. Aerial views show fields of circles created by the watery tracings of "quarter- or half-mile of the center-pivot irrigation pipe," created by center pivot irrigators which use "hundreds and sometimes thousands of gallons a minute."
Most center pivot systems now have drops hanging from a u-shaped pipe called a gooseneck attached at the top of the pipe with sprinkler heads that are positioned a few feet above the crop, thus limiting evaporative losses and wind drift. There are many different nozzle configurations available including static plate, moving plate and part circle. Pressure regulators are installed upstream of each nozzle to ensure each is operating at the correct design pressure. Drops can be used with drag hoses or bubblers that deposit the water directly on the ground between crops; this type of system is known as LEPA and is associated with the construction of small dams along the furrow length. Crops may be planted in straight rows or are sometimes planted in circles to conform to the travel of the irrigation system. Irrigation equipment can be configured to move in a straight line, where it is termed a lateral move, linear move, wheel move or side-roll irrigation system. In these systems the water is supplied by an irrigation channel running the length of the field.
The channel is positioned either in a line through the center. The motor and pump equipment are mounted on a cart by the supply channel; the cart travels with the machine. Farmers might choose lateral-move irrigation to keep existing rectangular fields; this can help them convert from furrow irrigation. Lateral-move irrigation is far less common, relies on more complex guidance systems, requires additional management compared to center pivot irrigation. Lateral-move irrigation is common in Australia. There, systems are between 500 and 1,000 meters long. Center-pivot irrigation uses less labor than many other surface irrigation methods, such as furrow irrigation, it has lower labor costs than ground-irrigation techniques that require digging of channels. Center-pivot irrigation can reduce the amount of soil tillage. Therefore, it helps reduce water