what is a bank transit number
An ABA routing transit number (ABA RTN) is a nine digit code, used in the United States, which appears on the bottom of negotiable instruments such as checks to identify the financial institution on which it was drawn.he first two digits of the nine digit RTN must be in the ranges 00 through 12, 21 through 32, 61 through 72, or 80. The digits are assigned as follows: 1  00 is used by the United States Government. 2  01 through 12 are the normal routing numbers, and correspond to the 12 Federal Reserve Banks.