Since 1972, when SSA began assigning SSNs and issuing cards centrally from Baltimore, the area number assigned has been based on the ZIP code in the mailing address provided on the application for the original Social Security card. The applicant's mailing address does not have to be the same as their place of residence. Thus, the Area Number does not necessarily represent the State of residence of the applicant, either prior to 1972 or since.
They even say (you can choose to believe them or not):
Note: One should not make too much of the "geographical code." It is not meant to be any kind of useable geographical information. The numbering scheme was designed in 1936 (before computers) to make it easier for SSA to store the applications in our files in Baltimore since the files were organized by regions as well as alphabetically. It was really just a bookkeeping device for our own internal use and was never intended to be anything more than that.
An authority is a person who can tell you more about something than you really care to know.