Via Census – Estimates of the number of people 18 and older in each state, Puerto Rico and the U.S.  The downloadable file will also include total population and the percentage of people 18 and older.

• Datasets are provided here to download for analysis in spreadsheet, statistical, or geographic information systems software. Files are in fixed-length ASCII format, each with a separate layout file, and in .csv, a generic spreadsheet format. Files include Federal Information Processing System (FIPS) codes, which uniquely identify geographic areas. Select population totals and totals by demographic characteristics are also available in formatted tables by level of geography on the Current Estimates Data page. For help with .csv files, click here.”