What is a transit ABA number and why does it matter?

Young man on bus, looking up his ABA number on his cellphoneImage: Young man on bus, looking up his ABA number on his cellphone

In a Nutshell

An ABA transit routing number is a nine-digit code assigned to U.S. banks that helps make paper check and electronic transactions possible. Learn how to find your bank’s routing number, what the numbers mean and why banks use them.

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If you’ve ever set up direct deposit, made an electronic transfer, paid a bill online or deposited a check via mobile deposit, you’ve probably had to provide your bank’s ABA transit routing number.

But where does an ABA number come from? How do you find yours? And what does it do?

We’ll answer those questions and more in this article.



What is an ABA transit number?

An ABA transit number, also known as a routing number, is a nine-digit number used to identify U.S. banks. This unique combination of digits makes it possible for specific financial institutions to easily transfer money to and from accounts. It’s typically used for common types of electronic transactions, such as direct deposits and online bill paying, along with paper check transactions.    

Who issues a routing number?

Routing numbers can only be issued to a bank by a company called Accuity, which serves as the official routing number registrar for the American Bankers Association, or ABA. In order to be eligible for a routing number, a bank must be chartered by the federal government or a state government and have an account with a Federal Reserve bank.

History of the routing number

Routing numbers were originally created by the ABA in 1910. Over the years, the purpose of transit numbers has evolved to adapt to modern-day needs related to the Federal Reserve System, electronic funds transfers, the advent of Magnetic Ink Character Recognition technology (or MICR), interstate banking and the Expedited Funds Availability Act.

How does an ABA transit number work?

ABA transit numbers act like an address and make it easy for banks to electronically transfer money between one another. Chances are that if you receive your paycheck through ACH direct deposit or you pay your bills online or over the phone, you’ve been asked to provide your routing number.

The numbers mean something

Nine digits make up your bank’s unique routing number. Each digit identifies something specific to your bank. Here’s how the digits break down.

  • Digits 1–4: Assigned by the Federal Reserve Routing System, the first four numbers in a routing number indicate the city and state where a bank is physically located.
  • Digits 5 and 6: These two numbers indicate the Federal Reserve bank that the bank’s electronic and wire transfers route through.  
  • Digit 7: This is the Federal Reserve check processing center that the bank was initially assigned.
  • Digit 8: This number indicates the bank’s Federal Reserve district.
  • Digit 9: The last digit in a routing number is used to verify that the routing number is valid.

Why do we need bank transit numbers?

Routing numbers are an essential part of modern banking. Whenever a check or electronic transaction happens between banks, the ABA transfer number is used to identify the banks responsible for paying or receiving the funds. Without routing numbers, you wouldn’t be able to enjoy banking features like mobile deposits, online bill pay or direct deposit. And it would be much harder for financial institutions to make sure money was moving between the right accounts.

Can a bank have more than one routing number?

Yes. The initial routing number that’s assigned to a financial institution corresponds with the Federal Reserve district and territory where the bank’s physical, principal office is located. If there’s more than one location, a bank may have up to nine extra routing numbers and can request more if needed.

Routing numbers can change due to bank mergers or acquisitions. New numbers might be assigned and old ABA transit numbers sometimes also get retired if a bank closes.

What happens if I use the wrong number?

Since a bank might have multiple routing numbers, it’s a good idea to always make sure you’re using the right number for the specific type of transaction you need to make. For example, your bank might have different routing numbers for branches located in different states or separate routing numbers for electronic payments, ordering checks, or domestic and international wire transfers.

How do I find my bank’s ABA transit number?

You can easily find your bank’s routing number, or ABA transit number, in a few different places.  

How to find it on a check

A check from your bank account features three key numbers along the bottom: the bank’s routing number, your account number and the check number. You’ll find your bank’s routing number in the lower left-hand corner of the check. It’s the first set of numbers when you read from left to right. The middle number is your checking account number, and your check number is last on the right.

Other places to find it

If you don’t have any checks to reference, you can contact your bank, check its website or log into your bank’s mobile app. Or, you can use the ABA’s online lookup. There are also other online databases you can check, but the ABA cautions users to steer clear, as these sites might not always have the most up-to-date information.


What’s next?

Now that you know more about what an ABA transit number is and how it works, you can start taking advantage of some convenient ways to use it. If you’re not already getting your paycheck deposited directly into your account, consider signing up with your employer.


About the author: Sarah Archambault is a freelance writer based in New England. She enjoys learning new ways to spend money wisely and helping others figure out how to make smart financial decisions. Sara… Read more.