Walnut is a city in the county of California. The town was incorporated on December 18, 1991, and has an approximate population of 30,000. It is located at the base of Mount San Antonio (nicknamed “Mt. Baldy”), near the Irvine Ranch Historic District. Walnut has grown from its rural roots into one of Orange County’s most affluent cities with over 1 million square feet (93,000 m2) of commercial space. The median home price is $1,895,000. Walnut is part of the Los Angeles metropolitan area; it lies approximately 25 miles (40 km) east of downtown Los Angeles and is part of the Greater Los Angeles Area. Oak linden trees were once prevalent in Walnut and remained in some areas.

At the beginning of the 20th century, walnut trees were plentiful along the West Branch of the San Gabriel River. A road that would eventually connect Rancho Cucamonga with Azusa was routed alongside it. The first known name for this area was “the walnut grove”; its post office operated from 1893 to 1907. The first official use of “Walnut” came in 1903, when the United States Post Office Department decided that several addresses could not be kept because of similar naming. The post office was named “Walnut Station” until the 1950s. The present city of Walnut is believed to have been named in 1904 for the “walnut tree” or other similarly-named trees that were common in the area. The town was incorporated in 1991.

Walnut has a Mediterranean climate (Köppen climate classification Csa), with warm, dry summers and mild, damp winters moderated by ocean breezes. Average temperatures approach freezing with the winter lows and rarely exceed 90 with summer highs; an average year sees about 12 days of frost. Rainfall averages 21 to 23 inches (53–59 cm) per year, most of which falls between November and March. Snow is unheard of in winter as temperatures stay above 70 degrees Fahrenheit (21°C), but is expected in the surrounding mountains of the San Gabriel Mountains, or Tehachapi Mountains. The 2010 United States Census reported that Walnut had a population of 29,718. The population density was 2,748.8 people per square mile (1,062.6/km²).

The best restaurants in Walnut, Irvine, California, are primarily upscale and include destinations like Mastro’s Steakhouse and The Cheesecake Factory. There are also notable ethnic restaurants, such as Pho King Awesome Vietnamese Cuisine and India Palace. The standout parks in Walnut are the expansive O’Neill Regional Park and the scenic Fryman Canyon Park. Other notable parks include Walnut Community Park and Pioneer Park. The top grocery stores in Walnut are Bristol Farms, Gelson’s, and Ralphs. The principal shopping centers in Walnut are The Promenade at Westlake Shopping Center, Plaza El Segundo, and Twelve Oaks Mall. Walnut is home to Lions Gate Entertainment which has produced movies such as the Saw franchise, Highlander, Underworld, The Exorcism of Emily Rose, Scary Movie 4, and The Long Kiss Goodnight. Disney’s Miracle Mile Shops is also in Walnut, which contains several clothing retailers like Urban Outfitters, Abercrombie & Fitch, American Eagle Outfitters, and other shops that are too many to list here.