The changing geography of population centroids in the United States between 1970 and 1990

Abstract

Population centroids are useful tools in describing the general trend of population movements. This paper uses population centroids to show the changing geography of the U.S. population between 1970 to 1990. Data of population counts of census tracts and census block groups were obtained from the Internet. With a geographical information system, weighted population centroids for each of the 48 states in the continental U.S., four census regions, and nine census divisions for 1970, 1980 and 1990 were calculated. The findings indicate that the westward movement of the U.S. population remains strong and that a southward trend of population movement can be clearly identified over the time periods examined.