From Census Bureau:
"A dataset is a file for public use to download for analysis in spreadsheet, statistical, or geographic information systems software. Subnational data files include Federal Information Processing System (FIPS) codes, which uniquely identify geographic areas."
"The population and housing unit estimates are released on a flow basis throughout each year. Each new series of data (called vintages) incorporates the latest administrative record data, geographic boundaries, and methodology. Therefore, the entire time series of estimates beginning with the most recent decennial census is revised annually, and estimates from different vintages of data may not be consistent across geography and characteristics detail. When multiple vintages of data are available, the most recent vintage is the preferred data."
"The vintage year (e.g., V2019) refers to the final year of the time series. The reference date for all estimates is July 1, unless otherwise specified."
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