soldiers in nearby army and navy camps. On January 25, 1917, an anti-prostitution drive in San Francisco attracted huge crowds to public meetings. At one meeting attended by 7,000 people, 20,000 were kept out for lack of room. In a conference with Reverend Paul Smith, an outspoken foe of prostitution, 300 prostitutes made a plea for toleration, explaining they had been forced into the practice by poverty. When Smith asked if they would take other work at $8 to $10 a week, the ladies laughed derisively, which lost them public sympathy. The police closed about 200 houses of prostitution shortly thereafter. The National Venereal Disease Control Act, which became effective July 1, 1938, authorized the appropriation of federal funds to assist the states in combating venereal diseases. Appropriations under this act were doubled after the United States entered the war. The May Act,3 which became effective with its signature by the President, July 11, 1941, armed the federal government with authority to suppress commercialized vice in the neighborhood of military camps and naval establishments in the United States. The May Act, which became law in June 1941, intended to prevent prostitution on restricted zones around military bases. It was invoked chiefly during wartime. See World War II U.S. Military Sex Education. Mortensen vs. United States, in 1944, ruled that prostitutes could travel across state lines, if the purpose of travel was not for prostitution. Later decades Conditions for sex trade workers changed considerably in the 1960s. The combined oral contraceptive pill was first approved in 1960 for contraceptive use in the United States. "The Pill" helped prostitutes prevent pregnancy. In 1967, New York City eliminated license requirements for massage parlors. Many massage parlors became brothels. In 1970, Nevada began regulation of houses of prostitution. In 1971, the Mustang Ranch became Nevada's first licensed brothel, eventually leading to the legalization of brothel prostitution in 10 of 17 counties within the state. In time, Mustang Ranch became Nevada's largest brothel, with more revenue than all other legal Nevada brothels combined. By World War II, prostitutes had increasingly gone underground as call girls. In 1971, the New York madame Xaviera Hollander wrote The Happy Hooker: My Own Story, a book that was notable for its frankness at the time, and considered a landmark of positive writing about sex. An early forerunner (1920s-1930s) of Xaviera Hollander's, both as a madam and author, was Polly