1.
Delaware County, Iowa
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Delaware County is a county located in the U. S. state of Iowa. As of the 2010 census, the population was 17,764, the county was named in honor of Delaware. According to the U. S. Census Bureau, the county has an area of 579 square miles. It has a hilly surface. There were 8,028 housing units, of which 7,062 were occupied, as of the census of 2000, there were 18,404 people,6,834 households, and 5,029 families residing in the county. The population density was 32 people per square mile, there were 7,682 housing units at an average density of 13 per square mile. The racial makeup of the county was 99. 28% White,0. 07% Black or African American,0. 10% Native American,0. 14% Asian,0. 01% Pacific Islander,0. 10% from other races, and 0. 30% from two or more races. 0. 66% of the population were Hispanic or Latino of any race,23. 00% of all households were made up of individuals and 11. 20% had someone living alone who was 65 years of age or older. The average household size was 2.66 and the family size was 3.15. In the county, the population was out with 29. 00% under the age of 18,7. 00% from 18 to 24,27. 60% from 25 to 44,21. 50% from 45 to 64. The median age was 37 years, for every 100 females there were 98.40 males. For every 100 females age 18 and over, there were 96.60 males, the median income for a household in the county was $37,168, and the median income for a family was $43,607. Males had an income of $30,712 versus $19,685 for females. The per capita income for the county was $17,327, about 6. 30% of families and 7. 90% of the population were below the poverty line, including 8. 50% of those under age 18 and 9. 80% of those age 65 or over. Delaware County is divided into townships, The population ranking of the following table is based on the 2010 census of Delaware County. † county seat National Register of Historic Places listings in Delaware County, Iowa County website

2.
Greeley, Iowa
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Greeley is a city in Delaware County, Iowa, United States. The population was 256 at the 2010 census and it is named for Horace Greeley. The town of Greeley experienced growth in the 1870s when the Davenport, greeleys longitude and latitude coordinates in decimal form are 42.585115, -91.341725. According to the United States Census Bureau, the city has an area of 0.37 square miles. As of the census of 2010, there were 256 people,101 households, the population density was 691.9 inhabitants per square mile. There were 108 housing units at a density of 291.9 per square mile. The racial makeup of the city was 100. 0% White,17. 8% of all households were made up of individuals and 7% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the family size was 2.89. The median age in the city was 40 years. 21. 9% of residents were under the age of 18,11. 7% were between the ages of 18 and 24,22. 7% were from 25 to 44,29. 3% were from 45 to 64, and 14. 5% were 65 years of age or older. The gender makeup of the city was 44. 5% male and 55. 5% female, as of the census of 2000, there were 276 people,112 households, and 84 families residing in the city. The population density was 729.7 people per square mile, there were 118 housing units at an average density of 312.0 per square mile. The racial makeup of the city was 100. 00% White, hispanic or Latino of any race were 0. 36% of the population. 23. 2% of all households were made up of individuals and 13. 4% had someone living alone who was 65 years of age or older, the average household size was 2.46 and the average family size was 2.86. In the city, the population was out with 22. 1% under the age of 18,8. 0% from 18 to 24,27. 2% from 25 to 44,26. 8% from 45 to 64. The median age was 41 years, for every 100 females there were 90.3 males. For every 100 females age 18 and over, there were 92.0 males, the median income for a household in the city was $35,000, and the median income for a family was $41,250. Males had an income of $28,750 versus $19,500 for females

3.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation