A routing transit number (RTN) is a nine digit bank code, used in the United States, which appears on the bottom of negotiable instruments such as checksidentifying the financial institution on which it was drawn. This code was designed to facilitate the sorting, bundling, and shipment of paper checks back to the drawer's (check writer's) account.

The RTN is also used by Federal Reserve Banks to process Fedwire funds transfers, and by the Automated Clearing House to process direct deposits, bill payments, and other such automated transfers.

The RTN number is derived from the bank's transit number originated by the American Bankers Association, which designed it in 1910.[1]