local women. In the weeks leading up to the riot, police had started to work to curb prostitution along Twelfth Street. On July 1, a prostitute was killed, and rumors spread that the police had shot her. The police said that she was murdered by local pimps. Detroit police used Big 4 or Tac Squads, each made up of four police officers, to patrol Detroit neighborhoods, and such squads were used to combat soliciting. Black residents felt police raids of after-hours drinking clubs were racially biased actions. Since the 1920s, such clubs had become important parts of Detroit's social life for black citizens; although they started with Prohibition, they continued because of discrimination against black people in service at many Detroit bars, restaurants, and entertainment venues. Employment and unemployment In the postwar period, the city had lost nearly 150,000 jobs to the suburbs. Factors were a combination of changes in technology, increased automation, consolidation of the auto industry, taxation policies, the need for different kinds of manufacturing space, and the construction of the highway system that eased transportation. Major companies like Packard, Hudson, and Studebaker, as well as hundreds of smaller companies, went out of business. In the 1950s, the unemployment rate hovered near 10 percent. Between 1946 and 1956, GM spent $3.4 billion on new plants, Ford $2.5 billion, and Chrysler $700 million, opening a total of 25 auto plants, all in Detroit's suburbs. As a result, workers who could do so left Detroit for jobs in the suburbs. Other middle-class residents left the city for newer housing, in a pattern repeated nationwide. In the 1960s, the city lost about 10,000 residents per year to the suburbs. Detroit's population fell by 179,000 between 1950 and 1960, and by another 156,000 residents by 1970, which affected all its retail businesses and city services. By the time of the riot, unemployment among black men was more than double that among white men in Detroit. In the 1950s, 15.9 percent of blacks were unemployed, but only 6 percent of whites were unemployed. This was partially due to the union seniority system of the factories. Except for Ford, which hired a significant number of black workers for their factories, the other automakers did not hire black workers until World War II resulted in a labor shortage. With lower seniority, black workers were the first to be laid off in job cutbacks after the