Willowbrook, alternatively named Willow Brook, is an unincorporated community and census-designated place (CDP) in Los Angeles County, California. The population was 24,295 at the 2020 census, down from 35,983 at the 2010 census.

Rosecrans Avenue is a major west-east thoroughfare in Los Angeles and Orange Counties, California, USA. It has a total length of 27.5 miles (44.3 km). The street is named after U.S. Union General William S. Rosecrans, who purchased 13,000 acres (5,300 ha) of Rancho Sausal Redondo southwest of Los Angeles in 1869. Rosecrans Avenue was originally named Drexel Avenue, and ran through the Rosecrans Rancho which is part of modern-day Gardena.