The 1987 Whittier Narrows earthquake occurred in the southern San Gabriel Valley and surrounding communities of Southern California, United States, at 7:42 a.m. PDT on October 1. The moderate magnitude 5.9 blind thrust earthquake was centered several miles north of Whittier in the town of Rosemead, had a relatively shallow depth, and was felt throughout southern California and southern Nevada. Many homes and businesses were affected, along with roadway disruptions, mainly in Los Angeles and Orange counties. Damage estimates ranged from $213–358 million, with 200 injuries, three directly-related deaths, and five additional fatalities that were associated with the event.

Whittier is a city in Southern California in Los Angeles County, part of the Gateway Cities. The 14.7-square-mile (38.0 km2) city had 87,306 residents as of the 2020 United States census, an increase of 1,975 from the 2010 census figure. Whittier was incorporated in February 1898 and became a charter city in 1955. The city is named for the Quaker poet John Greenleaf Whittier and is home to Whittier College. The city is surrounded by three unincorporated areas sharing the Whittier name, West Whittier-Los Nietos, South Whittier, and East Whittier, which combined are home to a larger population than Whittier proper.