Walnut is a city in Los Angeles County, California, United States. The city of Walnut obtained its name from the Rancho Los Nogales Mexican land Grant, nogales being the Spanish word for walnut. With exceptions to some busy intersections (such as near Mt. San Antonio College), the hilly and affluent city is considerably more relaxed in comparison to most nearby neighborhoods. The city covers nearly nine square miles (23 Square kilometer) and is home to more than 29,000 people and 600 businesses.