First Interstate Bank is a multi-state, $7.1 billion banking organization headquartered in Billings, Montana. First Interstate has evolved since 1968 from a single bank in Sheridan, Wyoming to operating 71 branches and over 100 ATMs in Montana, Wyoming, and South Dakota. First Interstate Bank is the principal subsidiary of First Interstate BancSystem, Inc., a financial holding company. They offer a number banking services including checking and savings accounts and loans for business and residential needs.