 In 1974, the company acquired Bank of Lake County, a California state-chartered bank that operated in the county adjacent to where Westamerica's existing operations were located.Gold County Bank in 1979 and Vaca Valley Bank in 1981 were each purchased by exchanging shares of the company for the shares of the acquired banks.These six banks were consolidated in mid-1983 into a single subsidiary bank, First National Bank of Mendocino County, which subsequently changed its name to Westamerica Bank.