When did dating minors become illegal?

The government was forced to propose the Criminal Law Amendment Act 1885, which raised the age of consent from thirteen to sixteen and clamped down on prostitution. In the United States, as late as the 1880s most states set the minimum age at ten to twelve (in Delaware, it was seven in 1895).

When did 18 become the legal age of consent?

1920 The ages of consent were raised across the U.S. during the late 19th century and the early 20th century. By 1920, 26 states had an age of consent at 16, 21 states had an age of consent at 18, and one state (Georgia) had an age of consent at 14. Small adjustments to these laws occurred after 1920.