Each year, as the United States of America prepares to celebrate its Independence Day, the urge to reexamine American history is inevitable. After all, it’s hard to escape what happened on July 4, 1776, when you’re marking a holiday known as the Fourth of July. But revisiting American history doesn’t have to mean sticking with those red-letter dates. Last year, at around this time, we asked 25 historians to nominate 25 moments that changed the nation, and the list they generated was eye-opening. Animated by the breadth and insight of that round-up, as well as the knowledge that it was only the tip of the iceberg, we’ve asked 25 new experts to chime in with their own nominations.
The only rules: the selections had to be “moments” (a broad social movement doesn’t count) and they had to have happened during the span of the 20th century, inspired by TIME founder Henry Luce having declared those years “the American century.” The results were, unsurprisingly, another fitting reminder of just how much can happen in 100 years—and of the way that a single day can change all that comes after. From laws that were passed with unintended consequences to scientific advancements that still affect our everyday lives to a celebrity debut that made a difference, each moment in its own way is an example of how history’s hinges work.
Reasons for nominations as told to Lily Rothman
The Mann Act Is Passed (June 25, 1910)
On June 25, 1910, the Mann Act, or White Slave Traffic Act, made it illegal to transport “in interstate or foreign commerce . . . any woman or girl for the purpose of prostitution or debauchery, or for any other immoral purpose.” Years of public alarm over “the traffic in women” and “white slavery”—language based on public officials’ assumptions that women in se* work must have been tricked or coerced—had produced the new law, but it would have consequences that went far beyond its immediate intent. The language of “immoral purpose” in the law proved to be elastic. Prosecutions under that rubric multiplied, catching unmarried consensual couples in its snare; federal authorities used the Mann Act to target individuals wanted for other reasons. Even more important in the long run, the Act’s creative use of the federal government’s constitutionally-mandated control over interstate commerce inaugurated the huge expansion of federal powers over citizens’ daily lives that would take place in the 20th century.
Nancy F. Cott is Jonathan Trumbull Professor of American History at Harvard University and president of the Organization of American Historians.