Pull federal agency contact, office, and personnel directory data from the USA.gov Federal Agency Directory API

Steps

1. The USA.gov Federal Agency Directory exposes a public API through the api.data.gov gateway; obtain a free api.data.gov API key and append it as the X-Api-Key header or api_key query parameter.
2. Call the agency list endpoint to retrieve all federal agencies cataloged in the directory; each record includes agencyName, agencyAcronym, website, mission, and a list of sub-agencies or offices.
3. Filter by parentAgency or agencyType (Cabinet, Independent, Board/Commission) fields to scope results to the relevant agency tier for your application.
4. Use the returned agencyId to retrieve detailed records including primary phone numbers, mailing addresses, and contact forms; use these to build automated agency contact routing for citizen-services applications.
5. Check the updatedDate field on records to detect stale entries; refresh your local copy when records have been updated more recently than your cached version.
6. Combine with the Federal Register API to cross-reference which agencies are actively publishing rulemaking documents, providing a signal of regulatory activity.