Walnut is a city in the eastern part of Los Angeles County in the U.S. state of California. Money's Best Places to Live ranked Walnut. The greater Walnut Valley is located between the steep San Jose Hills mountain range to the north, and the gentle Puente Hills to the south. Quality housing consists of master-planned single family homes ranging in size from 1,800 to 11,200 square feet (170 to 1,040 m2). 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. Walnut is one of the cities with the lowest crime rates in the San Gabriel Valley. The city covers nearly 9 square miles (23 km2) and is home to hundreds of businesses. According to the 2010 United States Census, Walnut has a median household income at one of the top-earning percentiles in the country at $101,250.