Westamerica Bank Routing Number

What is an ABA routing number?

An ABA routing number, also called a routing transit number (RTN), is a 9-digit code that identifies a U.S. financial institution in the payment system. It tells ACH transfers, Fedwire payments, and paper checks which bank to route money to. The format was created by the American Bankers Association in 1910 and is still the backbone of U.S. domestic payments.

What is the difference between a routing number and an account number?

Your routing number identifies the bank; your account number identifies your specific account at that bank. On a paper check, the routing number is the 9-digit number in the bottom-left, and the account number is to its right.

What is the Westamerica Bank routing number?

The Westamerica Bank routing number is 121140218. It is the primary ABA routing transit number registered to Westamerica Bank, headquartered in San Rafael, CA. A bank can hold more than one routing number, so this is the one on record for the institution, not necessarily the one printed on every check. The number comes from the FFIEC National Information Center institution record, last refreshed here on October 8, 2026.

What is the Westamerica Bank wire routing number?

This page lists 121140218, the primary routing number registered to Westamerica Bank. The record does not say whether the bank uses the same number for wire transfers, and many banks use a separate routing number for domestic wires. Confirm the wire routing number with Westamerica Bank before sending a wire.

Is ABA number 121140218 the routing number for Westamerica Bank?

Yes. ABA number 121140218 is the primary routing number registered to Westamerica Bank. Check it against the routing number on a check or in your online banking before sending an ACH payment, because a bank can use different numbers by region or product.

Which bank uses routing number 121140218?

Routing number 121140218 belongs to Westamerica Bank, headquartered in San Rafael, CA. It is the bank's primary ABA routing number (FDIC certificate 3430).

Routing numbers of similar-size institutions in California

Bank, San Rafael, CA

First Federal Savings and Loan Association of San Rafael: 321170596

Credit union, San Rafael, CA

Marin County Federal Credit Union: 321177340

Bank, Lodi, CA

Farmers & Merchants Bank of Central California: 121108441

Credit union, Vacaville, CA

Travis Credit Union: 321170839

Bank, Los Angeles, CA

CTBC Bank Corp. (USA): 122210406

Bank, Fremont, CA

Fremont Bank: 121107882

Bank, Sacramento, CA

River City Bank: 121133416

Bank, Roseville, CA

Five Star Bank: 121143037

All routing numbers in California