Walnut is a city in the eastern part of Los Angeles County, and according to the 2020 census, the city had a population of 28,430.[8]
The greater Walnut Valley is located between the steep San Jose Hills to the north and the gently sloping Puente Hills to the south. The city hosts a highly ranked public school system: the Walnut Valley Unified School District, which has been ranked by numerous sources as one of the top public-school districts in Southern California, as well as Mt. San Antonio College.
The city covers nearly 9 sq mi (23 km2) and is home to hundreds of businesses. According to the 2023 census bureau estimate, Walnut has a median household income at one of the top-earning percentiles in the country at $133,762.
The city's name is derived from the Rancho Los Nogales Mexican land grant, nogales being the Spanish word for "walnut trees"; the native California black walnut is a common tree, native to the San Jose Hills. The City of Walnut is a general law city incorporated on January 19, 1959.
The history of Walnut dates to the Indians who were of Shoshone origin. They were called Gabrielino Indians by the Spaniards because they lived in an area controlled by the San Gabriel Mission. Walnut was primarily used for the grazing of cattle and sheep by the Mission.
In 1871, the Lemon Creek Park area became the property of Sheriff William Rowland, who inherited the 29,000 acre ranch from his father, John Rowland. The modest structure served as the home of Mr. Meridith, ranch foreman for William Rowland. It was built in 1883. The adobe redwood ranch house is one of the few remaining original ranch style redwood and adobe structures in the area. On October 1, 1975, the State Landmark Committee placed the W.R. Rowland ranch house in the National Registry of Historical Places.