Rainier traced its roots back to the National Bank of Commerce, which was founded by Richard Holyoke in 1889.

Rainier Bancorp expanded into Alaska with the purchase of Anchorage's People's Bank & Trust in 1983[4] and into Oregon with the purchase of Gresham's Mount Hood Security Bank in 1986,[5] expanding further in Oregon in 1986 with the government-assisted purchase of Portland's failed Lincoln Savings & Loan Association[6] (not related to the Californian thrift of the same named that failed in 1989).

After a brief bidding war with First Bank System,[7] Rainier Bancorp.

[9] After the merger, Rainier Bancorporation was renamed Security Pacific Bancorporation Northwest, and Rainier National Bank was renamed Security Pacific Bank Washington.

[citation needed] Federal regulators, however, forced the divestiture of over half of the former Rainier Bank Washington state franchise (having been renamed Security Pacific Bank Washington, N.A.