In the middle of the 19th century, gold prospectors, sailors, and seasonal fruit and vegetable pickers lived in San Francisco's SRO hotels during the winter. SROs played a key role in providing housing for immigrant single adults and families, particularly those from China, Philippines, Japan and Latino countries; the SRO district was nicknamed "hotel city" due to the number of SRO hotels. By the late 1940s, the San Francisco Redevelopment Agency began working on "blight removal" and demolition, with thousands of SRO units destroyed to make way for redevelopment.