A U.S. ABA routing transit number contains nine digits and identifies a financial institution for payments.
Routing numbers were created for the American Bankers Association in the early 20th century. They originally helped identify banks involved in processing checks, and they are now used for electronic transactions such as direct deposits, ACH payments, and some wire transfers.
The routing number identifies the financial institution, while the account number identifies the customer’s particular account. Both numbers may be printed along the bottom of a paper check, although the exact information needed can vary by transaction type.
Routing numbers are not the same as card numbers, which identify payment cards, or SWIFT codes, which help identify institutions in international financial messaging. Some large banks can have multiple routing numbers for different states or transaction services.