- Area code records, prefix assignments, relief plans and forecasts: North American Numbering Plan Administrator (NANPA), nanpa.com.
- Canadian prefixes and exchange areas: Canadian Numbering Administrator (CNAC), cnac.ca.
- Unwanted-call complaints: U.S. Federal Trade Commission, Do Not Call Reported Calls data; Federal Communications Commission, Consumer Complaints data. Both are works of the U.S. government; complaints are unverified.
- Places and counties: U.S. Census Bureau Gazetteer files and FIPS place codes.
- Time zones: the IANA time zone database (public domain), applied by your browser for the local clock.
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