> In its original form the act made it a felony to engage in interstate or foreign commerce transport of "any woman or girl for the purpose of prostitution or debauchery, or for any other immoral purpose". Its primary stated intent was to address prostitution, immorality, and human trafficking, particularly where trafficking was for the purposes of prostitution
The reality however was that it was used to prosecute interracial marriage [2]:
> Also known as the White-Slave Traffic Act of 1910, the law was invoked over and over again to punish black men for their relationships with white women—affairs that challenged the racial status quo. Rooted in fears of women’s growing mobility and racist characterizations of the sexual appetites of non-white men, the law was designed to protect women against the supposed scourge of “white slavery,” a term used to refer to sex trafficking in the early 20th century.
Later there's a dark history of the FBI's involvements with the likes of Martin Luther King Jr, Malcolm-X, the Black Panthers and a bunch of other black leaders and movements.
[1]: https://en.wikipedia.org/wiki/Mann_Act
[2]: https://www.history.com/news/white-slave-mann-act-jack-johns...