BMO Routing Number: Cross-Border Banking with a Canadian Parent

BMO in the United States: a Canadian bank with Midwest roots

BMO's primary US routing number is 071025661, inherited from its longtime American subsidiary Harris Bank, which was founded in Chicago in 1882. The 0710 prefix places it squarely in the Federal Reserve Bank of Chicago's jurisdiction - fitting for a bank whose American story began on LaSalle Street. BMO, headquartered in Montreal, is one of Canada's "Big Five" banks and has operated in the United States for over 40 years through a series of acquisitions.

The bank operated as BMO Harris Bank in the US until September 2023, when it dropped the "Harris" name entirely as part of a rebranding effort to unify its North American identity. If you see references to BMO Harris Bank on old checks or documents, the routing number 071025661 still applies - only the branding changed.

The rebrand from BMO Harris and what changed (and what did not)

When BMO rebranded its US operations in 2023, customers kept their existing account numbers and routing numbers. No migration was required. The change was cosmetic - new signage, updated debit cards, a refreshed mobile app - but the underlying banking infrastructure remained the same. This is typical of rebrands as opposed to mergers: when the charter does not change, routing numbers stay put.

BMO also completed its $16.3 billion acquisition of Bank of the West (formerly owned by French bank BNP Paribas) in February 2023, expanding from its Midwest base into California, Colorado, and other Western states. Former Bank of the West customers were migrated to BMO systems over the following year, and most received the 071025661 routing number upon conversion.

SWIFT codes, transit numbers, and routing numbers: cross-border banking explained

One of the most common points of confusion for BMO customers is the difference between US routing numbers and Canadian transit numbers. BMO Canada uses a five-digit transit number plus a three-digit institution number (001 for BMO) to identify accounts, a completely separate system from the nine-digit ABA routing numbers used in the United States. You cannot use a Canadian transit number for a US ACH transfer, or vice versa.

For international wire transfers between BMO's US and Canadian operations, you need the SWIFT code: HATRUS44 for BMO US, and BOFMCAM2 for BMO Canada. Despite being the same parent company, wires between BMO US and BMO Canada are treated as international transfers and may incur foreign exchange fees and intermediary bank charges.

BMO routing numbers by region

Most BMO US customers use routing number 071025661. However, customers in Arizona may have routing number 071025661 as well (consolidated post-merger), while former Bank of the West customers should verify their routing number through BMO's online banking, as some legacy numbers from Bank of the West branches may still be in transition.

BMO offers a routing number lookup tool in its mobile app and online banking portal. For business accounts, the routing number is the same as personal accounts - BMO does not assign separate routing numbers by account type.

Cross-border business banking without the complexity

Companies that operate across the US–Canada border know the pain of juggling transit numbers, routing numbers, SWIFT codes, and FX fees between accounts that technically belong to the same bank. Slash simplifies the domestic side of that equation with a single US business account designed for operational clarity: straightforward routing details, real-time payment tracking, and built-in expense controls that remove the administrative overhead of managing business finances through a legacy branch bank.