A routing number is a nine-digit code that identifies a bank in the United States. It appears on checks, on deposit slips, and in online banking. It is used to route electronic payments, like direct deposits and ACH transfers, to the correct bank. Without it, the payment system would not know where to send the money.

The number has a structure. The first two digits identify the Federal Reserve district. The next four identify the specific bank. The last digit is a check digit, calculated from the others, which allows software to catch typing errors. The American Bankers Association assigns routing numbers and maintains the registry. A bank may have multiple routing numbers for different purposes, such as paper checks, electronic transfers, and wire transfers.

Routing numbers are not the same as account numbers. The routing number identifies the bank. The account number identifies the specific account. Both are needed for an electronic transfer. On a check, the routing number is the first set of digits at the bottom, followed by the account number and the check number.

Routing numbers are public, unlike account numbers. They are printed on checks and published on bank websites. But fraudsters use them to create fake checks and phishing emails. Customers should verify any request for bank details and never share account numbers or passwords in response to unsolicited messages.