What is an ABA number/routing number?

An ABA number (also known as routing number or routing transfer number) is a sequence of nine numeric characters used by banks to identify specific financial institutions within the United States. An ABA number is used for wires and electronic automatic clearing house (ACH) transactions such as electronic funds transfer, direct deposit, direct payment of consumer bills, e-checks, and tax payments, among others. Your bank assigned each account a unique number. There is no standard for the size of the number but it is always printed next to the ABA\Routing Number at the bottom of the check.