ABA numbers are used for ACH transfers. ACH transfers are only available to U.S. contractors with U.S. bank accounts. You can choose another withdrawal method if you are not a U.S. resident.
The ABA number is usually be found on the checks issued by your bank, at the bottom of each check, in the first group of nine digits. If you aren’t sure what they are or where to find them, the best thing to do is to call or visit your bank to ask them.
Question Arises, What is the routing number?
The ABA routing number is a 9-digit identification number assigned to financial institutions by The American Bankers Association (ABA). This number identifies the financial institution upon which a payment is drawn. Routing numbers are sometimes referred to as “check routing numbers”, “ABA numbers”, or “routing transit numbers” (RTN). Routing numbers may differ depending on where your account was opened and the type of transaction made.
Please note that you should not confuse ABA Routing Number with the Swift Code. For checking Swift or BIC codes you should go here…
http://www.swift-codes.org/