Bank of the West began as Farmers National Gold Bank of San Jose, California, in 1874. When all bank notes became convertible to gold or silver in 1880, the bank converted from a gold national bank and changed its name to the First National Bank of San Jose, California.
In 1970, Banque Nationale de Paris (BNP) established the French Bank of California. Later that decade, First National Bank of San Jose changed its name to Bank of the West.1 In 1979, BNP bought Bank of the West and merged in the French Bank of California.

Throughout the 1980s and 1990s, Bank of the West bought several other banks and branches. In 1987, Bank of the West bought Bank of Los Gatos. This was followed by the 1990 purchase of Central Banking Systems; the 1991 purchase of 30 branches in northern California from failed Imperial Savings and Loan; the 1992 purchase of Atlantic Financial Federal Savings Bank from the Resolution Trust Corporation; the 1993 purchase of 15 branches in northern California from Citibank; the 1995 purchase of NorthBay Savings Bank, headquartered in Petaluma, California; and the 1997 purchase of branches from Bank of America and Coast Federal Bank.

In 1995, First Hawaiian Bank established Pacific One Bank to hold 30 branches in Washington, Oregon, and Idaho that it acquired from West One Bank when that bank was acquired by U.S. Bancorp and had to divest certain assets, due to the number of preexisting branches of U.S. Bank in the region. Three years later, in 1998, BNP and First Hawaiian Inc., the parent of First Hawaiian Bank and Pacific One Bank, created a company under the BancWest Bancorp name to hold Bank of the West and First Hawaiian Bank, with Bank of the West absorbing Pacific One. The creation of BancWest Bancorp caused the now-called BNP Paribas’ (BNPP) ownership of the holding company to fall to 45%. BNPP also agreed not to increase its ownership of the bank holding company before November 2001.