Unmarried sex is still a sincrime in several states.

Unmarried cohabitation:
Six states continue to make it a crime for an unmarried man and a woman to cohabit together: Florida, Michigan, Mississippi, North Carolina, North Dakota, Virginia and West Virginia fall into this category. Arizona and New Mexico decriminalized unmarried cohabitation in 2001. North Dakota repealed its law in 2007. The validity of the North Carolina law is questionable due to a trial court ruling in 2006 declaring it unconstitutional.

Fornication:
Seven states and the District of Columbia make it a crime for a man and a woman to engage in consensual intercourse in private: Idaho, Massachusetts, Minnesota, South Carolina, Utah, Virginia, West Virginia, and D.C. fall into this category.

unmarriedamerica.org