Willowbrook, alternatively named Willow Brook,[3] is an unincorporated community and census-designated place (CDP) in Los Angeles County, California.

Long before the name "Willowbrook" was given, willows and a slow, shallow brook separated this portion of the Los Angeles plain from the rest of it.

The original rancho boundary of the 1840s was a lone, streamside willow tree along the present intersection of 125th Street and Mona Boulevard.

Winter rains brought up fine ryegrass stands between gravelly ridges left by the long-ago floods of the Los Angeles River.

[6] The first branch of the Los Angeles County Free Library was established in Willowbrook: "It was opened in April, 1913, in a private house, but has been located for several years since in the post office building.

The deep lots, sometimes 300 feet or 91 meters in depth, attracted working-class families, especially newcomers to Southern California.

The Big Red Cars offered fast and convenient transport to shops in downtown Los Angeles and jobs in port areas of Long Beach and San Pedro.

During the Depression years, residents used the land behind their homes to cultivate fruits and vegetables, run hogs, and raise chickens.

This use of land, along with the vacant lots filled with mustard plants, enhanced the rural appearance of the area.

Increased suburban growth occurred in Willowbrook after the end of the Depression and World War II, but not so much that the agricultural character of the area was drastically modified.

[6] The blend of agricultural and residential land use persisted at Willowbrook into the early 1980s, when a redevelopment plan drawn up by the Watts Labor Community Action Committee from 1965 to 1993 and funded by Los Angeles County caused the area to lose its rural character.

The appearance of present-day Willowbrook is similar to other communities in the South Central section of Los Angeles because of this.

[8] According to the United States Census Bureau, the CDP has a total area of 3.8 square miles (9.8 km2), over 99% of it land.

According to the 2010 United States Census, Willowbrook had a median household income of $34,005, with 31.5% of the population living below the federal poverty line.

[34] The Los Angeles County Sheriff's Department (LASD) operates the Century Station in Lynwood, serving Willowbrook.

[35] The United States Postal Service Willowbrook Post Office is located at 2241 East El Segundo Boulevard in the CDP.

The station is located in the Century Freeway (Interstate 105) median, above the intersection of Imperial Highway and Wilmington Avenue in Willowbrook.

[41] Zoned elementary schools within the CDP include Anderson, Carver, Jefferson, King, and Lincoln.

[36][45] The California Office of Environmental Health Hazard Assessment has issued a safe eating advisory for any fish caught in Magic Mike Lakes due to elevated levels of mercury and PCBs.