1980 point population coverage for the Conterminous United States
A point coverage was created from the 1980 Master Area Reference File
(MARF) of the U.S. Census Bureay.  Each point represents the center of a
census tract, though some tracts were split.  A 1980 population is
associated with each point.  Populations for 1970, 1982, 1984, and 1985 were
inferred from county population …