Bank routing number or routing transit number (RTN) is a nine digit number used to identify financial institution in a transaction.
Most common transaction types where routing numbers are used are ACH and wire transfers.
Some banks and credit unions may have multiple routing numbers serving different purposes, geographical regions or branches.
Therefore it is important to ensure that you are using correct routing number before you initiate a money transfer.
There are multiple ways to finding bank or credit union routing number.
The most common one if by looking it up in your checkbook.
Routing numbers are printed on the bottom of a check:
Find Routing Number on Your Check
However it is important to note that some financial institutions have different routing numbers for electronic and paper transactions.
Routing numbers can often be found on online banking sites of the financial institution.
In some cases you would need to login into online banking to find correct routing number.
If you are still not sure which routing number to use contact your bank/credit union directly.
You can call phone number listed on your debit card or use one of the methods listed on contact page of online banking.
Below are links to pages listing routing number for some of the largest financial institutions: