Why do some banks have more than one routing number in the US?

For example, Bank of America has several routing numbers:

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Why not use the same routing number for all types of transactions?

  • 1
    Wells has a different routing number for wire transfers also. I think Ally has even more different routing numbers.
    – quid
    Nov 10, 2016 at 19:54
  • @quid Thanks I have modified the question accordingly. Nov 10, 2016 at 19:58
  • 2
    This also sometimes comes about from bank mergers. If Banks A and B merge, they might keep both routing numbers, so that customers can keep using the routing and account numbers they already had, without having to update payment info, order new checks, etc. Nov 10, 2016 at 20:58
  • My BofA routing number is different from yours. I started with Nation's Bank back in the 90s (in Texas), so I guess +1 to Nate and Keith?
    – JPhi1618
    Nov 11, 2016 at 18:40
  • @JPhi1618 is your routing number 111000025 or 113000023 (i.e., bankofamerica.com/deposits/manage/faq-routing-numbers.go -> Texas)? Nov 11, 2016 at 18:43

3 Answers 3


A lot of it has to do with bank mergers, acquisitions, etc. over the years. In order to reduce the confusion generated with routing numbers changing, they are kept around. This happened to me when US Bank took over the bank I used after it failed. This was in the 2008-2009 timeframe and the routing number from the original bank is still used. In fact, checks from the original bank are still good.

  • 1
    This make a lot of sense. If they changed the routing # when the bank changes ownership, they'd have to issue all checking accounts new check books. That would be a lot of waste, and much easier to just keep the old routing #.
    – Chris
    Nov 11, 2016 at 0:47
  • 1
    In Germany, after merges of smaller banks, the old bank often gets the routing number (here called "Bankleitzahl", bank routing number) from the bank obtaining it, or the new, merged bank gets a completely new one.
    – glglgl
    Nov 11, 2016 at 10:41

The numbers came into existence long before computers/automation of processing. They are designed to help banks internally work out where money is coming from (location) and what it's for (task).

As a consequence, large banks with exposure to multiple geographic markets and domains of service use multiple numbers to show them exactly what's going on.

This historical legacy remains in place today, as no one wants to undertake the monumental task of unpicking the routing number system.

  • This is the best answer, but it's not about no one wanting to change it. It's about knowing where/from the money is going to. Like a zip code. A routing number can be used to send "the money" to a regional clearing house.
    – coteyr
    Nov 11, 2016 at 17:02

The wire transfer numbers are different because they work across a different network (SWIFT - Society for Worldwide Interbank Financial Telecommunication), which handles international interbank transfers. As such, they'll be assigned different numbers than the ABA Routing Transit Number (ABA RTN) network, used for transactions between banks in the United States.

  • I the example in the image this is correct.
    – coteyr
    Nov 11, 2016 at 17:02
  • SWIFT addresses are at least partly and usually mostly or entirely alphabetic (letters), not (just) numbers. They do differ from ABA, but both numbers in the Q are ABA (and confirmed as BofA in my copy of the FRB's ACH directory). Nov 12, 2016 at 7:01

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