ASLRRA's Associate Membership consists of four categories:

1. Associate Business Members are suppliers of goods and services to the short line and regional railroad industry.
2. Associate Railroad Members are tourist or excursion railroads, passenger railroads, and transit railroads.
3. Associate Sustaining Members are those companies and agencies that service the short line and regional railroad industry on a regulatory basis or are customers. This category is open to Class I railroads, state DOTs, rail shippers, and third party logistics providers.
4. Associate Switching Members are any non-railroads that provide switching services to private industry and are not deemed a railroad by the Surface Transportation Board.