Caching Now

Feature Story


Our latest favorite tale from the world of geocaching

or benchmark hunting.  

The U.S. Center of Population
Every ten years, after tabulating how many people are in this country, the U.S. Census Bureau calculates the nation’s mean center of population. That point is defined as the place where an imaginary flat, weightless, and rigid map of the United States would balance perfectly if all residents were of identical weight.

The center of population provides a fascinating glimpse into the history of the U.S. It follows the sweep of the nation’s brush stroke across American’s population canvas—a sweep that reflects the settling of the western frontier, waves of immigration, and internal migrations. The center of population was first calculated in 1790, when it was near Chestertown, Maryland. As the nation grew and developed, the center of population has steadily moved west and south. After Maryland, it passed through Virginia, West Virginia (although that state did not exist at the time), Ohio, Kentucky, Indiana, and Illinois before entering Missouri in 1980.

Now, the area around Edgar Springs, Missouri, shares an honor held by only 21 other U.S. communities. The current center of population, determined after the 2000 census, is at latitude 37 41 49 N, longitude 91 48 35 W, which is 2.8 miles east of Edgar Springs. This new point is approximately 35 miles southwest of the 1990 center of population near Steelville, Missouri, and more than 1,000 miles from the original center in Maryland.
Beginning with the 1960 census, the U.S. Coast and Geodetic Survey (now the National Geodetic Survey), began placing special commemorative disks at or near each center of population location. On April 23, 2001, an 8-inch diameter bronze marker manufactured by Berntsen was set by NGS in Edgar Springs, the nearest town to the 2000 center. The marker was set with cooperation from the U.S. Census Bureau, the Missouri Department of Natural Resources, Phelps County, and the city of Edgar Springs.
Because of the importance of this mark, NGS surveyed it extremely accurately, resulting in adjusted coordinates of 37 42 28.97929 N and 91 52 03.69031 W. You can read a story about the monumentation ceremony on the NGS website. You may also want to view the datasheet for the mark, which has the PID AJ3110.
Many states have also determined where their center of population is and set a marker there. You can view maps of the locations on the NGS website, and see a table of the exact coordinates on the Census Bureau website. (Here’s a tip: those coordinates are in decimal degrees, but if you copy and paste them into Google Maps, it will plot the location and translate them into degrees/minutes/seconds for you.)

Perhaps, armed with your GPS unit, you can have an adventure to a part of your state where you’ve not been before! If there’s a marker there (or nearby), take a photo of it, along with some photos of the area. If you’re able to attend a monumentation ceremony, even better! If there isn’t a marker, you can still get photos of yourself or your friends at the designated location. (In that case, please include a closeup photo of your GPS receiver to confirm the correct location.) Email your best photos to us at We’ll publish some in a future issue of Caching Now!

Originally published on March 17, 2008.

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