The geographic center of the United States is a point approximately 20 mi (32 km) north of Belle Fourche, South Dakota at . It has been regarded as such by the U.S. National Geodetic Survey (NGS) since the additions of Alaska and Hawaii to the United States in 1959.
This is distinct from the contiguous geographic center, which has not changed since the 1912 admissions of New Mexico and Arizona to the contiguous United States, and falls near the town of Lebanon, Kansas. This served as the overall geographic center of the United States for 47 years, until the 1959 admissions of Alaska and Hawaii moved the geographic center of the overall United States approximately 550 mi (885 km) northwest by north.
While any measurement of the exact center of a land mass will always be imprecise due to changing shorelines and other factors, the NGS coordinates identify the spot as an uninhabited parcel of private pastureland approximately 12 mi (19 km) east of the cornerpoint where the South Dakota–Wyoming–Montana borders meet. According to the NGS data sheet, the actual marker is "set in an irregular mass of concrete 36 inches below the surface of the ground."
For public commemoration, a nearby proxy marker is located in a park in Belle Fourche, where one will find a flag atop a small concrete slab bearing a U.S. Coast and Geodetic Survey Reference Marker.
Contiguous United States
While any measurement of the exact center of a land mass will always be imprecise due to changing shorelines and other factors, the NGS coordinates are recognized in a historical marker in a small park at the intersection of AA Road and K-191. It is accessible by a turn-off from U.S. Route 281.
In a technical glitch, a farmstead northeast of Potwin, Kansas, became the default geolocation of 600 million IP addresses (due to a lack of fine granularity) when the Massachusetts-based digital mapping company MaxMind changed the putative geographic center of the contiguous United States from 39.8333333,−98.585522 to 38.0000,−97.0000.
Its inscription reads:
The GEOGRAPHIC CENTER of the UNITED STATES
LAT. 39°50' LONG. −98°35'
NE 1/4 – SE 1/4 – S32 – T2S – R11W
Located by L.T. Hagadorn of Paulette & Wilson – Engineers and L.A. Beardslee – County Engineer. From data furnished by U.S. Coast and Geodetic Survey.
Sponsored by Lebanon Hub Club. Lebanon, Kansas. April 25, 1940
An American flag usually flies atop a pole placed on the monument. A covered picnic area and the U.S. Center Chapel, a small eight-pew chapel, are nearby.
Method of measurement
In 1918, the Coast and Geodetic Survey found this location by balancing on a point a cardboard cutout shaped like the U.S. This method was accurate to within 20 miles, but while the Geodetic Survey no longer endorses any location as the center of the U.S., the identification of Lebanon, Kansas, has remained.
In the 1969 Disney movie The Computer Wore Tennis Shoes, the final question of the college knowledge program is 'A small Midwest city is located exactly on an area designated as the 'geographic center of the United States.' For ten points and $100,000, can you tell us the name of that city?' The answer of Lebanon, Kansas is accepted as correct.
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- Position of the Geographic Center of Area, Mean and Median Centers of Population: 2010 from the U.S. Census Bureau website[dead link]
- http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=PU2386 designates the "Center" as 44 58 02.07622(N) 103 46 17.60283(W)
- "Geographical Centers of the United States" (PDF). USGS Publications Warehouse. U.S. Department of the Interior Geological Survey. 1964. Retrieved 13 May 2015.
- Hill, Kashmir (April 10, 2016). "How an internet mapping glitch turned a random Kansas farm into a digital hell". Fusion. Retrieved October 23, 2020.
- "The actual center is about a half mile away in the center of a former hog farm." (kansastravel.org Archived August 25, 2006, at the Wayback Machine)
- Walter H. Schoewe, "Kansas and the geodetic datum of North America", Transactions of the Kansas Academy of Science 51 (1948) 117–124, www.jstor.org
- "Geographic Center of the United States" (PDF). National Geodetic Survey Publications. National Geodetic Survey. Retrieved 13 May 2015. Includes a reprint of Adams, Oscar S. (1932). "Geographical Centers". The Military Engineer. 24 (138): 586–587. Describes cardboard method used "a number of years ago".
- Keith Stokes (2008-06-01). "Geographic Center of the United States". Kansastravel.org. Retrieved 2016-03-07.
- "The Geographical Center of the Lower 48 United States, at Lebanon, Kansas". Archived from the original on August 25, 2006. Retrieved June 1, 2006.
- In the Middle of Nowhere, a Nation’s Center, New York Times
- Smith County Map, KDOT
- Kansas Travel article
- Center for Land Use Interpretation article about the origins and accuracy of the marker
- Roadside America article
- USGS information
- The Center of the United States article about applying mathematical methods to geography