With housing consisting almost entirely of single-room-occupancy hotel rooms, studio and one bedroom apartments, the Tenderloin historically housed single adults and couples. After World War II, with the decline in central cities throughout the United States, the Tenderloin lost population, creating a large amount of vacant housing units by the mid-1970s. Beginning in the late 1970s, after the Vietnam War, the Tenderloin received large numbers of refugees from Southeast Asia—first ethnic Chinese from Vietnam, then Khmer from Cambodia and Hmong from Laos. The low-cost vacant housing, and the proximity to Chinatown through the Stockton Street Tunnel, made the area appealing to refugees and resettlement agencies. Studio apartments became home for families of four and five people and became what a local police officer called "vertical villages." The Tenderloin quickly increased from having just a few children to having over 3,500 and this population has remained. A number of neighborhood Southeast Asian restaurants, bánh mì coffee shops, ethnic grocery stores, video shops, and other stores opened at this time, which still exist.