At the start of the 20th century, both immigration and urbanization were rapidly increasing. People were moving from the countryside into cities, and for the first time in American history, women were able to support themselves financially in these urban centers and gained unprecedented physical and financial freedom. With this newfound freedom also came an American fear of sexuality. Young people were changing the norms of courtship, and anxiety spread through the country about these new cities being the perfect breeding ground for debauchery.
By 1907, a panic was spreading through America. People began to believe that women were being forced into prostitution on a large scale by a malicious and established network of individuals. Horrific stories of women being drugged and kidnapped spread like wildfire through the media, feeding the hysteria.
The government responded in a couple of different ways, but most notably, the federal government put into effect the Mann Act, making it a crime to "transport or cause to be transported, or aid or assist in obtaining transportation for" or to "persuade, induce, entice, or coerce" a woman to travel "in interstate or foreign commerce, or in any Territory or the District of Columbia" if the travel was "for the purpose of prostitution or debauchery, or for any other immoral purpose ... whether with or without her consent."
What I find the most interesting about the Mann Act is that, as the moral panic of "The White Slave Trade" began to fade, the government used the Mann Act to target its political opponents. One notable example is Charlie Chaplin. Many officials disliked Charlie Chaplin because of his progressive views, supposed support of communism, and controversial relationships with younger women.
In the early 1940s, Chaplin was in a relationship with a younger actress, Joan Barry. As their relationship ended less than amicably, Joan accused him of transporting her across state lines for sexual purposes, thus bringing the Mann Act into play. In 1944, Chaplin was indicted under the Mann Act and, while later acquitted, the whole ordeal completely tarnished his reputation. America had lost its trust in Chaplin, and in 1952, when trying to travel back into America, he had his permit revoked, thus very nearly ending his career in America.