Azusa (Tongva: Azuksa, meaning "skunk") is a city in the San Gabriel Valley region of Los Angeles County, California, United States, at the foot of the San Gabriel Mountains and located 20 miles (32 km) east of downtown Los Angeles.

[7] Azusa is located along historic Route 66, which passes through the city on Foothill Boulevard and Alosta Avenue.

[10] A backronym, "Azusa stands for everything from A to Z in the U.S.A.", has been a phrase used for many years by organizations such as the Chamber of Commerce to promote the city.

In 1844, Arenas sold the rancho's land to Henry Dalton, an English immigrant and wealthy merchant from the Pueblo of Los Angeles, for $7,000.

He renamed it Rancho Azusa de Dalton, and had built a winery, distillery, vinegar house, meat smokehouse, and flour mill.

In the end, Dalton owned an unbroken expanse of land from present-day San Dimas to the eastern edge of Pasadena.

With the cession of California to the United States following the Mexican–American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored.

As required by the Land Act of 1851, a claim for Rancho San Francisquito was filed with the Public Land Commission in 1852 and confirmed by the Commission in 1853, but rejected by the US District Court in 1855, on the grounds that Henry Dalton was not, at the time of the grant, a citizen of Mexico.

Dalton had borrowed money from Los Angeles banker Jonathan S. Slauson to fund 24 years of litigation, and had to sign the land over to him in 1880.

[19] The Pacific Electric also provided the community with passenger rail service via its Monrovia-Glendora Line from 1907 to 1951.

According to the United States Census Bureau, the city has a total area of 9.7 square miles (25 km2); over 99% of it is land.

A decade later, Miller relocated its operations to the nearby city of Irwindale and the Azusa facility ceased production in 1980, eventually being demolished.

Aerojet, a rocket engine manufacturer, had a plant in Azusa from World War II to 2001.

[49] Aerojet sold the property in 2001 to Northrop Grumman Corporation, but remained the Responsible Party for the pollution.

In a 2002 court decision, Aerojet and seven other San Gabriel Valley groundwater polluters agreed to provide funding to build and operate six water-treatment facilities.

Effective with the 2020 California Primary election, they are held on a Tuesday after the first Monday in March of even-numbered years.

On March 5, 2016, Azusa became the eastern terminus of the first phase of the Foothill Extension of the L Line (now the northeastern terminus of the A Line) which previously operated between Los Angeles Union Station and Sierra Madre Villa station in eastern Pasadena.

[57] The A Line operates along former Atchison, Topeka and Santa Fe Railway right-of-way purchased by the Los Angeles County Metropolitan Transportation Authority in 1993.

[59] A popular running gag on the long-running radio comedy The Jack Benny Program involved a character voiced by Mel Blanc announcing the arrival or departure of a train to or from "Anaheim, Azusa, and Cuc-a-monga," all three then being small towns without rail service at the time.

The city's name appeared in the title of the Jan and Dean song "Anaheim, Azusa, & Cucamonga Sewing Circle, Book Review and Timing Association" in 1964.

[61] In Hold Back the Dawn (1941), Emmy Brown (Olivia de Havilland), a schoolmarm from Azusa, recites the claim that it "stands for everything from A to Z in the U.S.A." The same happens in A Woman's Secret (1949), with Susan Caldwell (Gloria Grahame), born and raised in Azusa, describing the town's name as "kind of a made-up name".

In Six Feet Under (TV series), a professor sends an assistant to Azusa and recites the same claim, saying “that’s how you guys name your towns here”.