Westamerica Bancorporation is the holding company for Westamerica Bank and its subsidiaries. The commercial and regional community bank, headquartered in Fairfield, California, has $4.7 billion in assets and more than 90 branches in Northern and Central California. Westamerica Bancorporation is a northern California bank holding company comprising two principal subsidiaries: Westamerica Bank and Bank of Lake County, both community banks serving individuals and business clients. The holding company also oversees the operations of Community Banker Services Corporation and Westcore, which perform certain administrative functions. Westamerica Bancorporation operates more than 50 branches in 12 California counties including Marin, Napa, and Sonoma. From a handful of small community banks in the early 1970s operating under a bank holding company organization, Westamerica had expanded by the mid-1990s to a position as one of the largest networks of community banks serving northern California and as a market share leader in many of the local areas it served. Formed in 1972 under the name of Independent Bankshares Corporation, the holding company consolidated three previously unaffiliated banks: Bank of Marin, Bank of Sonoma County, and First National Bank of Mendocino County, which was formerly known as First National Bank of Cloverdale. The new structure began operations in 1973.