Walnut Creek, residential city (1990 pop. 60,569), Contra Costa co., W Calif., in the San Francisco Bay area; inc. 1914. It is the trade and shipping center of an extensive agricultural area where walnuts, apples, vegetables, and nursery stock are among the major products. There is food processing and the manufacture of machinery, industrial glass, chemicals, medical instruments, and electronic equipment. Business growth developed greatly in the city and its environs in the late 20th cent., and industry has become increasingly important to the economy. Numerous industrial research firms, corporate headquarters, and a naval weapons station are in Walnut Creek.