NOAA's NATIONAL OCEAN SERVICE MARKS THE USA'S POPULATION CENTER
May 2, 2001 If the United States was a flat, rigid, weightless surface, and the entire population of 281,421,906 weighed exactly the same, where would the perfect balance point be? Every ten years, the Census Bureau and NOAA's National Ocean Service work together to answer that question, by pin pointing the Center of Population. This year they determined the area to be around Edgar Springs, Mo., a rural community with a population of less than 200. (Click NOAA image for larger view of NOAA geodesist Dave Doyle as he "finishes" setting the survey mark. Please note this is a large file. Please Credit "NOAA.")
Until the completion of the 2000 census, not many people had ever heard of Edgar Springs, Mo. Now, this quiet corner of mid-America has become known as the "Center of Population." The Geography Division of the Census Bureau determined the Center based on computations used over the years. The exact location is approximately 34.7 miles southwest of the 1990 population center, located near the town of Steelville, Mo.
According to the Census Bureau, historically the Center of Population has followed a trail that reflects immigration and migration. Since 1790, the location has moved westerly, then a more southerly pattern. The new Center of Population is more than 1,000 miles from the first Center in 1790, which was located near Chestertown, Md.
Beginning in 1960, the U.S. Coast and Geodetic Survey, now the National Ocean Service, established a high accuracy geodetic control monument at or near the computed location, to commemorate the completion of this important activity. On April 23, members of NOAA's National Geodetic Survey set an 8 inch, 25 pound, polished brass survey marker in a massive concrete post during a dedication ceremony. (Click NOAA image for larger view of crowd of about 200 watching the setting of the Center of Population.)
Following the dedication ceremonies,
the NGS team, assisted by surveyors from the Missouri Department
of Natural Resources, performed a high accuracy three-dimensional
geodetic survey, using both global
positioning system measurements and precision leveling observations,
that included connections to nearby existing geodetic stations
in the National
Spatial Reference System. Upon completion of the analysis
and adjustment of the GPS and leveling measurements, NGS will
determine the latitude, longitude, ellipsoid and orthometric
heights to an accuracy of better than 3 cm, relative to the NSRS.
They will load the data into the NGS Data Base, where it becomes
a permanent part of the NSRS, available to all surveyors, engineers,
cartographers and other users of high accuracy spatial data.
(Click NOAA image of Center of Population plate replica.)