For the U.S., the Census Bureau maintains demographic datasets down to the state and county level. Many other countries have similar government bodies with the same mission. There are multiple datasets available, but a great place to start is the QuickFacts dataset.

QuickFacts maintains statistics for all U.S. states and counties, along with cities and towns that have a population of 5,000 or more. It includes statistics on population size and density, age and sex, race, housing, education, economy, income, business, and health. The dataset uses the Federal Information Processing Standards (FIPS) code as the identifier. The FIPS code is normally what you would use to link to your IoT data.

The FIPS code is a five-digit identifier that identifies counties (or county equivalents) in the United States. The first two digits signify the state and the last three identify the county. A list of FIPS codes can be downloaded from https://www.census.gov/geo/reference/codes/cou.html.

The U.S. Census Bureau also maintains some useful geospatial datasets that have demographic information already integrated. Information about the Topologically Integrated Geographic Encoding and Referencing (TIGER) datasets is available at https://www.census.gov/geo/maps-data/data/tiger.html: