The eighteenth Constitutional amendment initiated the Prohibition Era in the United States at the end of World War I. As Northern Californian vineyards were major producers of American wines, the significant loss in business forced many, including Sacramento's two largest vineyards, to close; the city was not sympathetic to either prohibition or the temperance movement, although elements of the temperance movement were noticeable in the Sacramento area. In addition, the river front city border with Yolo County, known as the West End, devolved into a slum that was filled, notably, with speakeasies, bordellos, and buildings used for gambling. The slum was regarded one of the worst west of those in Chicago. As an exchange for locating Mather AFB near Sacramento, a member of the United States Department of War demanded that the city deal with the West End's problems.