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
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
Time in the United States
Time in the United States, by law, is divided into nine standard time zones covering the states and its possessions, with most of the United States observing daylight saving time for the spring and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation. Official and precise timekeeping services are provided by two federal agencies: the National Institute of Standards and Technology; the clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations. It is the combination of the time zone and daylight saving rules, along with the timekeeping services, which determines the legal civil time for any U. S. location at any moment. Before the adoption of four standard time zones for the continental United States, many towns and cities set their clocks to noon when the sun passed their local meridian, pre-corrected for the equation of time on the date of observation, to form local mean solar time.
Noon occurred at different times but time differences between distant locations were noticeable prior to the 19th century because of long travel times and the lack of long-distance instant communications prior to the development of the telegraph. The use of local solar time became awkward as railways and telecommunications improved. American railroads maintained many different time zones during the late 1800s; each train station set its own clock making it difficult to coordinate train schedules and confusing passengers. Time calculation became a serious problem for people traveling by train, according to the Library of Congress; every city in the United States used a different time standard so there were more than 300 local sun times to choose from. Time zones were therefore a compromise, relaxing the complex geographic dependence while still allowing local time to be approximate with mean solar time. Railroad managers tried to address the problem by establishing 100 railroad time zones, but this was only a partial solution to the problem.
Weather service chief Cleveland Abbe had needed to introduce four standard time zones for his weather stations, an idea which he offered to the railroads. Operators of the new railroad lines needed a new time plan that would offer a uniform train schedule for departures and arrivals. Four standard time zones for the continental United States were introduced at noon on November 18, 1883, when the telegraph lines transmitted time signals to all major cities. In October 1884, the International Meridian Conference at Washington DC adopted a proposal which stated that the prime meridian for longitude and timekeeping should be one that passes through the centre of the transit instrument at the Greenwich Observatory in the United Kingdom; the conference therefore established the Greenwich Meridian as the prime meridian and Greenwich Mean Time as the world's time standard. The US time-zone system grew from this, in which all zones referred back to GMT on the prime meridian. In 1960, the International Radio Consultative Committee formalized the concept of Coordinated Universal Time, which became the new international civil time standard.
UTC is, within about 1 second, mean solar time at 0°. UTC does not observe daylight saving time. For most purposes, UTC is considered interchangeable with GMT, but GMT is no longer defined by the scientific community. UTC is one of several related successors to GMT. Standard time zones in the United States are defined at the federal level by law 15 USC §260; the federal law establishes the transition dates and times at which daylight saving time occurs, if observed. It is the authority of the Secretary of Transportation, in coordination with the states, to determine which regions will observe which of the standard time zones and if they will observe daylight saving time; as of August 9, 2007, the standard time zones are defined in terms of hourly offsets from UTC. Prior to this they were based upon the mean solar time at several meridians 15° apart west of Greenwich. Only the full-time zone names listed below are official. View the standard time zone boundaries here; the United States uses nine standard time zones.
As defined by US law they are: From east to west, the four time zones of the contiguous United States are: Eastern Time Zone, which comprises the states on the Atlantic coast and the eastern two thirds of the Ohio Valley. Central Time Zone, which comprises the Gulf Coast, Mississippi Valley, most of the Great Plains. Mountain Time Zone, which comprises the states and portions of states that include the Rocky Mountains and the western quarter of the Great Plains. Pacific Time Zone, which comprises the states on the Pacific coast, plus Nevada and the Idaho panhandle. Alaska Time Zone, which comprises most of the state of Alaska. Hawaii-Aleutian Time Zone, which includes Hawaii and most of the length of the Aleutian Islands chain. Samoa Time Zone, which comprises American Samoa. Chamorro Time Zone, which comprises Guam and the Northern Mariana Islands. Atlantic Time Zone, which comprises Puerto Rico and the US Virgin Islands; some United States Minor Outlying Islands are outside the time zones defined by 15 U.
S. C. § exist in waters defined by Nautical time. In practice, military crews may
Norfolk is a city in Madison County, United States, 113 miles northwest of Omaha and 83 miles west of Sioux City at the intersection of U. S. Routes 81 and 275; the population was 24,210 at the 2010 census. It is the principal city of the Norfolk Micropolitan Statistical Area. In late 1865 three scouts were sent from a German Lutheran settlement near Ixonia, Wisconsin, to find productive, inexpensive farmland that could be claimed under the Homestead Act. From the Omaha area they followed the Elkhorn River upstream to West Point. Finding that area too crowded, they continued up the river. On September 15, they reached the junction of the Elkhorn and its North Fork, chose that area as a settlement site. On May 23, 1866, a party of 124 settlers representing 42 families from the Ixonia area set out for northeast Nebraska in three wagon trains, they arrived at the new site on July 15. A second group of settlers from Wisconsin arrived in July 1867; the original name of the colony was a variant of "North Fork", but accounts differ on the exact name: "Northfork", "Nor'fork", "Nordfork" are all suggested.
The name was submitted to federal postal authorities, at some point was transmuted to "Norfolk". The pronunciation "Norfork" is used by Nebraskans; the North Fork settlement was named the county seat in 1867. In 1875 a series of elections changed this. In the first of these Norfolk, which at the time had 45 voters, was eliminated. In a subsequent election Madison was chosen over Battle Creek; the Fremont and Missouri Valley Railroad was built after the discovery of gold in the Black Hills in South Dakota. It ran from the Omaha area up the Elkhorn valley across northern Nebraska and into South Dakota, its arrival at Norfolk in 1879 connected the city through Wisner to Blair on the Missouri. The Omaha and Black Hills branch of the Union Pacific ran north from the railroad's main line at Duncan to Norfolk; the Chicago, St. Paul, Minneapolis & Omaha Railroad was completed to Norfolk in 1882; the development of these railway connections led to significant growth in the city. In 1886 Norfolk's population reached 1000.
A street railway system and a public water supply were established in 1887. In 1888 a franchise was granted to the Norfolk Electric Light Company, the Nebraska Telephone Company was given a right-of-way for "general telegraph and telephone business"; the Nebraska legislature created the Insane Asylum in Norfolk in 1885. In 1920, the institution's name was changed to the Norfolk State Hospital; as of 2010, it was a 120-bed institution providing the initial phase of treatment to sex offenders. In 1900, the city had a population of 3,883, nearly quadruple its population of a decade earlier. By 1910, it had more than 6,000 people, comprising one-third of Madison County's population of 19,101. In 1915, petitions were filed for an election to move the county seat from Madison to Norfolk; the measure, failed to secure the necessary number of votes. In the 1910s, development began on the Meridian Highway as a direct north-south route across the United States; the 1924 completion of the Meridian Bridge across the Missouri River at the Nebraska-South Dakota border made the highway a continuous year-round thoroughfare.
In 1926, it was designated as U. S. Highway 81. A second federal highway, U. S. Highway 275, received its designation in 1939. During World War II, the segment from Norfolk to O'Neill was a portion of the Strategic Network of Highways. Air travel developed in Norfolk beginning with the establishment of a flying school in 1928; the school's field expanded and was improved. In 1942 the WPA began construction of a municipal airport at the site. Although construction materials were limited during World War II, Norfolk received priority as an auxiliary field to several war-related airports, including Sioux City Air Field. After the war Norfolk congressman, Karl Stefan, a member of the Congressional Air Policy Board, used his influence to secure further funding for the airport. Commercial passenger flight through the airport began in the early 1950s. In the 1970s, another attempt was made to move the county seat from Madison to Norfolk. In a 1975 county-wide election, the move's proponents failed to secure a simple majority.
A 60% majority would have been necessary for the measure to pass. On September 26, 2002, three gunmen robbed a US Bank branch in Norfolk, killing five people in the process; this was the nation's deadliest bank robbery in at least a decade. Norfolk is located at 42°1′42″N 97°26′01″W. According to the United States Census Bureau, the city has a total area of 10.78 square miles, of which, 10.69 square miles is land and 0.09 square miles is water. As of the census of 2010, there were 24,210 people, 9,910 households, 6,005 families residing in the city; the population density was 2,264.7 inhabitants per square mile. There were 10,625 housing units at an average density of 993.9 per square mile. The racial makeup of the city was 88.0% White, 1.6% African American, 1.4% Native American, 0.6% Asian, 6.3% from other races, 2.0% from two or more races. Hispanic or Latino of any race were 12.1% of the population. There were 9,910 households of which 31.0% had children under the age of 18 living with them, 46.3% were married couples living together, 10.6% had a fe
U.S. Route 81
U. S. Route 81 is a major north-south highway that extends for 1220 miles in the central United States and is one of the earliest United States Numbered Highways established in 1926 by the US Department of Agriculture Bureau of Public Roads; the route of US-81 follows that of the old Meridian Highway which dates back as early as 1911. The highway has alternately been known as part of the Pan-American Highway. In the segment in the State of Oklahoma, the highway corresponds to the old Chisholm Trail for cattle drives from Texas to railheads in Kansas in the 1860s and 1870s; as of 2004, the highway's northern terminus is just north of Pembina, North Dakota at the Canada–US border. At this point, it is routed along Interstate 29 and continues northward into Manitoba on Highway 75 that leads to Winnipeg, its southern terminus is in Fort Worth, Texas, at an intersection with Interstate 35W. Between the inception of the numbered highway system in 1926 through 1991, US 81's southern terminus was at the Mexican border in Laredo, Texas.
In 1991, the terminus was moved to San Antonio. The route was shortened to its present length of 1,234 miles in 1993, when the terminus was moved to Fort Worth. In both cases, the dropped portions of US 81 were replaced by Interstate 35. Portions of former US-81 south of Fort Worth continue to exist as business loops of I-35; the decommissioning of portions of U. S. 81 that have been displaced by concurrent Interstate highways means that U. S. 81 no longer extends from the Canada–US border to the Mexico—US border, while one of its "children", U. S. Route 281 does extend to both borders; as a result of decommissioning portions of US 81, the length of U. S. 81 is 672 miles shorter than of its "child." US 81 at its inception in 1926 followed the route of State Highway 2, which began in Laredo and passed through San Antonio, Austin and Fort Worth before passing over the Red River into Oklahoma four miles north of Ringgold. The 1936 Official Map of the Highway System of Texas shows the route labeled both as US 81 and S.
H. 2. It was cosigned with U. S. Highway 83 for 18 miles from Laredo to 2 miles south of Webb, with U. S. Highway 79 for 18 miles from Austin north to Round Rock, with U. S. Highway 77 for 33 miles from Waco to Hillsboro. In 1940 U. S. Highway 287 was extended south into Texas, a 67-mile stretch from Fort Worth northwest to Bowie was cosigned with US 81; the Summer 1941 Texas Highway Map shows this pairing, the current southern terminus of US 81 is still cosigned with US 287. The Spring and Summer 1949 Texas Highway Department Official Map designates the length of US 81 from Laredo to Fort Worth as part of the National System of Interstate Highways, but no numeric designation is given, it was not until 1959 that parts of US 81 in Texas appeared on the Texas Official Highway Travel Map cosigned with Interstate 35 shields. Succeeding maps reflect the slow completion of I-35 and I-35W over the stretch of US 81 between Laredo and Fort Worth, with the 1978-79 Texas Official Highway Travel Map showing only a 14-mile section from Encinal north to 3 miles south of Artesia Wells as incomplete, the 1980 Texas Official Highway Travel Map showing that section completed.
In 1980, US 81 was cosigned with I-35 and I-35W except where the Interstate bypassed towns, with US 81 providing the main route through town and reconnecting with I-35 on the other side. The longest section of US 81 in 1980 not cosigned with the Interstate ran from I-35 in Hillsboro 20 miles north to I-35W, just north of Grandview. Enid, El Reno and Duncan are major Oklahoma towns on the highway. Among the elders throughout the small towns that are dotted along Route 81 in Oklahoma, the sixth meridian is known among the locals as the "Indian Meridian" but Route 81 is not known as the "Indian Meridian Highway." The Indian Meridan is located some 40 miles east and parallel of U. S. Route 81. By pure coincidence, the Chisholm Trail of the Post-Civil-War decades followed along the corridor of present-day Route 81. Nearly all of US-81 in Kansas is either expressway; the route enters Kansas as a two-lane near Caldwell. From South Haven to Wichita it parallels Interstate 35, known as the Kansas Turnpike in that area.
After South Haven, the only town of any significance along US 81 until Wichita is Wellington, just west of the Turnpike along U. S. Route 160. At Wichita, US-81 joins Interstate 135; the two highways remain joined with I-135's mile markers taking precedence. Interstate 135 ends at Interstate 70 but US-81 continues as a freeway to Minneapolis as an expressway passing through Concordia before exiting the state north of Belleville; the alignment of US-81 from Wichita to Salina prior to the completion Interstate 135 is intact. The prior alignment ran from where current US-81 breaks off for Interstate 135 at 47th street, north through Wichita along Broadway street. Old US-81 parallels Interstate 135 to Newton. Ol US-81 follows current K-15 through Newton between an interchange with US-50 and Hesston Road, where old US-81 breaks northwest onto Hesston road. Old US-81 travels through the small Kansas towns of Hesston and Elyria, before turning to the nort
Vehicle registration plates of Nebraska
The U. S. state of Nebraska first required its residents to register their motor vehicles in 1905. Registrants provided their own license plates for display until 1915, when the state began to issue plates. All state-issued plates were made of steel until 1947. With the exception of 1945, all plates have been issued in pairs since 1922. In 1956, the United States and Mexico came to an agreement with the American Association of Motor Vehicle Administrators, the Automobile Manufacturers Association and the National Safety Council that standardized the size for license plates for vehicles at 6 inches in height by 12 inches in width, with standardized mounting holes; the 1955 issue was the first Nebraska license plate. Nebraska established a county-code system for its passenger and motorcycle plates in 1922, with one- or two-digit codes assigned to each county in order of the number of registered vehicles in the county at that time; these codes remained constant through 1950. For 1951, letter codes were used.
One-letter codes were assigned to the first counties whose names began with those letters, while all other counties were assigned two-letter codes consisting of the initial letter and the next available letter in their names. There were three exceptions: Douglas County, the most populous in the state, was assigned single-letter X to increase capacity; the numeric code system was reintroduced with the codes the same as before. It remains in use to this day, except in Douglas and Sarpy Counties, which adopted an uncoded ABC 123 serial format in 2002. Nebraska license plates 1969-present
U.S. Route 275
U. S. Route 275 is a north–south United States highway, it is a branch of US 75 terminating at that route in Council Bluffs, Iowa. The highway's northern terminus is in O'Neill, Nebraska, at an intersection with U. S. Highway 20 and U. S. Highway 281, its southern terminus is near Rock Port, Missouri, at an intersection with U. S. Highway 136. U. S. 275 is signed north -- south in Iowa, while in Nebraska, it is signed east -- west. U. S. Route 275 begins at an intersection with U. S. Route 136 1 mile west of Rock Port, it travels to the northwest through Atchison County for 16 miles. U. S. Route 275 crosses into Iowa 1 1⁄2 miles south of Hamburg, it enters Hamburg and intersects Iowa Highway 333, which connects to Interstate 29 1 1⁄2 miles to the west. North of Hamburg, it intersects Iowa 2, the two routes share 5 miles of road. US 275 and Iowa 2 bypass Sidney on its east side, east of Sidney, US 275 and Iowa 2 separate. From east of Sidney, US 275 continues north for 20 miles through Tabor until it intersects U.
S. Route 34 east of Glenwood. US 275 and US 34 overlap for 8 miles bypassing Glenwood. West of Glenwood, US 34 and US 275 split at an interchange with I-29. For 13 miles, US 275 overlaps I-29, ending at an interchange with Iowa 92 in southern Council Bluffs. Turning west, US 275 / Iowa 92 travel together for 5 miles in Iowa and cross the new South Omaha Veterans Memorial Bridge over the Missouri River. US 275 enters Nebraska in Omaha in the South Omaha neighborhood paired with Nebraska Highway 92, it goes through Omaha as a four-lane highway until meeting Nebraska Highway 31. The street designations for US 275 in Omaha are, from east to west, Missouri Avenue, L Street, Industrial Road and West Center Road, it crosses the Elkhorn River, which it will follow for most of the rest of the route separates from NE 92. It becomes freeway until Fremont, it meets U. S. Route 30 and they are paired together around Fremont until meeting U. S. Route 77. US 275 meets Nebraska Highway 91 and separates from US 77 near Winslow.
It turns northwest with NE 91 and they separate near Scribner, Nebraska. US 275 goes north through West Point, turns northwest through Wisner, turns west. At Norfolk it meets U. S. Route 81, it continues west-northwest, meets U. S. Route 20 near Inman and the two routes overlap until US 275 ends at an intersection with U. S. Route 281 in downtown O'Neill. At its creation in 1932, US 275 ran from Council Bluffs to Missouri. In 1939 the route was extended northwest into Nebraska. In 1963 US 275 was truncated to its current end in northwestern Missouri. Prior to 1963, US 275 extended south to St. Joseph; the route followed current U. S. Route 136 east from Rock Port to its intersection with U. S. Route 59 near Tarkio south with US 59 to St. Joseph. Before November 2001, US 275 ran alongside the Union Pacific tracks between Waterloo and Fremont, Nebraska; this routing was replaced by a new freeway segment built as part of a project to connect Fremont via freeway to Omaha. This segment is called Reichmuth Road in Douglas County and Bell Street in Fremont.
Prior to July 1, 2003, US 275 followed a winding two-lane road between Council Bluffs and Glenwood, Iowa. The segment moved to a concurrency with U. S. Route Interstate 29 that day as part of a mass decommissioning of highways in Iowa; this road is now Mills County and Pottawattamie County Road L35. Mileposts reset at state line crossings. In Nebraska, US 275 is considered an east–west highway, its mileposts run from west to east U. S. Route 75 U. S. Route 175 U. S. Route 275 Business - Fremont, Nebraska Endpoints of US highway 275 Nebraska Transportation On New Bridge