<human>:  When did the citrus industry start in Los Angeles County?
<bot>: Citrus was first grown in Los Angeles in 1857. In the 1880s, citrus groves were planted in the area near the Santa Monica Mountains, and they quickly became a significant part of the local economy. The citrus industry continued to grow through the 20th century, and today there are over 1,500 acres of citrus trees in the area.