What is a wire transfer & what are Regions wire transfer routing numbers? What is my routing/transit number? When are the business day cutoff times for deposits and other transactions? When will my funds be available for use? Where can I find the routing and/or transit number on my checks? 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.