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View detailsBMO 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, founded in Chicago in 1882. The 0710 prefix places it 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 to unify its North American identity. Old checks or documents referencing BMO Harris Bank still carry routing number 071025661 — only the branding changed.
The Bank of the West acquisition
In February 2023, BMO completed its $16.3 billion acquisition of Bank of the West, formerly owned by French bank BNP Paribas, 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, with most receiving the 071025661 routing number upon conversion. If you were a Bank of the West customer, verify your current routing number through BMO's online banking portal to confirm the migration is complete.
Routing numbers and the rebrand
When BMO rebranded its US operations in 2023, customers kept their existing account numbers and routing numbers — no migration required. The change was cosmetic: new signage, updated debit cards, a refreshed app. This is typical of rebrands as opposed to mergers: when the charter doesn't change, routing numbers stay put. Most BMO US customers use 071025661. BMO offers a routing number lookup tool in its mobile app and online banking portal to confirm your specific number.
SWIFT codes, transit numbers, and cross-border banking
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 — a completely separate system from the nine-digit ABA routing numbers used in the US. 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, the SWIFT codes are HATRUS44 for BMO US and BOFMCAM2 for BMO Canada. Despite being the same parent company, wires between the two are treated as international transfers and may incur foreign exchange fees and intermediary bank charges.
Cross-border business banking without the complexity
Companies operating 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 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.
