CMS produces a "Zip Code to Carrier Locality File" that is available for download from the CMS Fee Schedules – General Information website. For each zip code, the file will include carrier numbers, locality numbers, and state codes. The file will also include an indicator for urban, rural or a low density (qualified) area. The CMS website only maintains the most recent version of the file.
Historical versions of the file may be found on www.archive.org. To search for a specific year:
- Insert the specific URL (https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/FeeScheduleGenInfo/index.html) into the search box.
- The results returned all of the dates in which this specific URL was captured.
- A search performed on 6/30/17 found the website was captured, including the zipped files, several times back to 2011.
See article: Using Internet Archive to Find Historical Documents and Downloadable Data Files for more information about how to use Internet Archive.