Here it is http://www.kansastravel.org/geographicalcenter.htm :)

The geographic center of the 48 contiguous states is in Lebanon, Kansas. If you were to include Alaska and Hawaii, it would move both westward and northward (and, depending on your definition, the center might move more into the center of the globe). To determine where the geographic center of all 50 states, you would have to define what you mean by distance from the center... is it distance along the surface of the globe, or straight-line distance THROUGH the globe. If your definition is the distance along the surface of the globe, in 1959 the National Geodetic Survey said that Belle Fourche, South Dakota was the geographic center of all 50 states. If your definition is the straight-line distance through the earth, the geographic center of the 50 states would probably be some distance down into the ground from Belle Fourche. Of course, if you add territories like Puerto Rico, Guam, etc, lordy only knows where your geographic center would be!