NHGIS Time Series Tables
An NHGIS time series table links together comparable statistics from multiple U.S. censuses in one downloadable bundle. A table is comprised of one or more related time series, each of which describes a single summary statistic (e.g., the count of occupied housing units) measured at multiple times (e.g., each census year from 1970 to 2010) at selected geographic levels (e.g., states or counties).
The set of covered statistics, years, and geographic levels varies from table to table according to which categories are available, and at which levels, at different times. Tables may also differ in the method of geographic integration they use to align geographic units across time.