Age of consent for sexual relations outside of marriage. But most states have laws allowing marriage for minor girls. The man doesn't have to be within 3 years. California of all places allows girls as young as 13 to marry with the consent of a parent and a judge. I think those laws were put in place a long time ago to protect girls who ended up pregnant. Rather than destroy a young man's life he was allowed to marry the girl. Nowadays the view is young women are officially children until they magically cross the 18 yr old threshold(use to be 21!) and nothing must get in the way of them getting an education.Age of consent is 16 in many states, but the age difference usually can’t be more than 3 years. States vary.