Pío Pico State Historic Park is the site of El Ranchito, also known as the Pío Pico Adobe or Pío Pico Mansion, the final home of Pío Pico, the last Governor of Alta California under Mexican rule and a pivotal figure in early California history. Located in Whittier, California, at 6003 Pioneer Blvd. near Whittier Blvd. and Interstate 605, it is California Historical Landmark No. 127, listed as "Casa de Governor Pío Pico". Just west of the park is the San Gabriel River. Across the river is the city that bears his name—Pico Rivera. The park consists of the adobe and about three acres of surrounding land.

Don Pío de Jesús Pico IV was a Californio politician, ranchero, and entrepreneur, famous for serving as the last governor of Alta California under Mexican rule. A member of the prominent Pico family of California, he was one of the wealthiest men in California at the time and a hugely influential figure in Californian society, continuing as a citizen of the nascent U.S. state of California. His legacy can be seen in the numerous places named after him, such as the city of Pico Rivera, Pico Boulevard in Los Angeles, Pio Pico State Historic Park, and numerous schools that bear his name.