Graham National Bank was originally chartered in August of 1901 by a group of local ranchers who built a building at the corner of Fourth and Oak Street, on the northwest corner. In 1967, a new building was constructed on the northeast corner of the square. The first building was sold in 1967 to become the Graham City Hall 

Since building the new facility in 1968, several major additions and remodelings have enhanced the bank's ability to provide the needed space and environment for customer comfort and quality service.

Ownership of the bank changed in 1968, 1982 and 1993. Since 1993, Graham National Bank has been a community bank that is owned by local and area business people. In 2022, the bank is known as Graham Interbank.

Graham Interbank is progressive and is actively involved in supporting the community and it's needs. The bank has modern banking facilities which include the main bank building, a six land drive-in bank, and three ATM facilities. Additionally, the bank offers voice response and internet banking.