On a ranch eighteen miles southeast of this site, a bronze plate marks the Geodetic Center of the United States, the primary station for all North American surveys. A cross-mark engraved on the plate fixes the tiny point on which the surveys of a sixth of the world's surface depend. The U.S. Coast and Geodetic Survey located it in 1901, and later Canada and Mexico adopted the point and its supporting system as the base for their surveys, after which it became known as the North American Datum. In this sense, a Kansas pasture stands to the lines and boundaries of this continent as Greenwich stands to the longitude of the world. It is distinct from the Geographic Center of the United States, which lies forty-two miles north in Smith County.