Montclair is a city in the Pomona Valley, in southwestern San Bernardino County, California. The population was 36,664 in the 2010 United States Census.
The earliest known inhabitants of the area were from the Serrano tribe of Native Americans. The Serrano established their village along a creek named Arroyo de los Alisos, now named San Antonio Creek, which flowed along a route that is now Mills Avenue, the western border of the city.
In 1897, a "Township of Marquette" was founded within the borders of the modern city of Montclair. In 1900, a 1,000 acres (4.0 km2) tract of land was surveyed and named "Monte Vista". A small settlement to the south of Monte Vista was established in 1907 and named "Narod". Throughout the first half of the 20th century, the settlement was largely devoted to citrus orchards. The Monte Vista tract experienced growth in residential development after the Second World War, and the tract was incorporated as the city of Monte Vista on April 25, 1956. Due to conflict with the Post Office, which refused to open an office in Monte Vista due to a name conflict with a community in Northern California, the city was renamed Montclair on April 8, 1958.