In Ohio, it is illegal for five or more women to live together in the same residence. This law is often called the woman's dormitory law. The rationale behind this law is that it would promote immoral behavior and lead to public health problems. According to one critic of the law, The underlying assumption seems to be that if women are left to their own devices, they will engage in all sorts of sexual excesses and general debauchery.
There is no evidence that this law has ever been enforced. In fact, it appears to be largely unknown outside of legal circles. Nevertheless, it remains on the books and could theoretically be used to prosecute women who choose to live together.