Banks print routing numbers on the bottom of checks and other documents, alongside the account number, explains Bank of America. Online portals provide routing numbers for use in electronic wire transfers. For example, the Bank of America website provides a state-by-state guide to obtaining its routing numbers.
A bank's routing number usually comprises nine digits and identifies the financial institution from which a payment comes, notes Bank of America. Your routing number differs according to where you opened the account (location and branch) and the type of transaction. Transactions that require routing numbers include paper transactions, such as checks; electronic transactions, such as direct deposits; and electronic wire transfers. If you are unsure of the correct routing number to use, contact the bank directly.