A routing number, also known as a routing transit number (aka RTN) or ABA number, is a nine-digit code the American Bankers Association assigns to identify a financial institution in a transaction. It quite literally helps route the transaction to the correct bank.
Every day, it helps millions of people get their payroll direct deposits, tax refunds, and government benefits. They can also use them to send ACH (Automated Clearing House) payments and wire transfers.

Do you still have checks? You can find the routing number at the bottom left of your checks in those funny characters. Incidentally, it’s the one that’s not your account number or the check number. 

Probably the easiest way to find your routing number is to just check your online account. How you find it depends on whether you’re looking on a desktop or mobile device, but it’s easy, either way.
To find it on your desktop, log in and go to your account summary. It doesn’t matter which account you choose unless the accounts are in different states or you need other information, such as your account number. 
You can find the routing number by clicking the “Routing number” link located next to your account number under the account name or at the bottom of the summary. The numbers you need will pop up.

Yes. “ABA” stands for the American Bankers Association, the organization that created these numbers. You will often see the terms “ABA number” and “routing number” used interchangeably.

Banking systems were historically localized. Even though Wells Fargo is a national bank, it maintains different routing numbers based on where you originally opened your account. This helps the bank process transactions more efficiently based on regional banking hubs.

Most of Texas uses one routing number, but El Paso has its own. This is because El Paso operates on a different regional infrastructure (fun fact: it’s also on a different electrical grid and time zone than most of the state!).