An ABA routing number is a nine-digit code used in the United States to identify financial institutions. It helps facilitate the transfer of funds between banks, ensuring that money is sent to the correct location. Each bank has a unique routing number, which is essential for processing checks, direct deposits, and electronic payments. The American Bankers Association established the routing number system in 1910 to streamline banking operations. This number is often found on checks, typically located at the bottom left corner, and is crucial for various transactions, including wire transfers and automated clearing house (ACH) payments.