SAM.gov

The Public Location Services API provides Location Services data (Country, State, City, and ZIP) and is to be used when validating location data that is being submitted to the SAM.gov ONLY. SAM.gov is not the authoritative source for location data and is agglomerating data from 3rd parties to operate the application. Location Public Services API used to support only United States. As part of GENC updates, currently Location Services State API supports Foreign Countries aswell. https://open.gsa.gov/api/location-public-api/