The citrus industry in Upland and neighboring Ontario continued to thrive, and by the 1930s, citrus had become the dominant agricultural crop for California. In 1936, the revenue from the citrus industry totaled $97,000,000. This was second in profit only to the California petroleum industry, which totaled $159,500,000. At the height of citrus production, the industry produced sixty percent of the nation's citrus supply and twenty percent of the world's supply. This success continued for citrus growers until the mid-1940s, when the citrus industry as a whole began its decline. After World War II, land values began to skyrocket, and growers began to sell their land to developers.