Versions and retirement: how long each API version is supported, and how we announce retirements, is in our API versions and retirement policy. What's new lists each release.
The Texas A&M Geoservices point-in-polygon Census Intersection engine can be used from desktop and/or web applications via the Web Service interfaces listed below. The only required information is the API key, which is available in your account profile page. You may want to read the technical details.
https://dev.geoservices.tamu.edu/Services/CensusIntersection/WebService/CensusIntersectionWebService_V02_94.asmx
https://dev.geoservices.tamu.edu/Services/CensusIntersection/WebService/CensusIntersectionWebServiceHttp_V02_94.aspx?