Santa Paula (sănˈtə pôlˈə) [key], city (1990 pop. 25,062), Ventura co., S Calif., on the Santa Clara River in a fertile valley that yields citrus fruits, avocados, vegetables, flowers, nursery products, and walnuts; laid out 1875, inc. 1902. Fruit packing and oil production are major industries. Manufactures include concrete and paper products and lingerie. The Union Oil Company, founded in Santa Paula in 1890, operates a notable oil museum there.