On March 22, 1972, the United States Congress passed the Equal Rights Amendment to the U.S. Constitution, and sent it to the states for ratification.

Here are some things you might not know about the Equal Rights Amendment.

• It was ratified by 35 of the necessary 38 states before a 1982 deadline.

• Defense of traditional gender roles was one of the main strategies employed by opponents of the amendment. Some argued that it would have meant the end of single-sex bathrooms.

• Supporters of the amendment are still trying to gain support in states that had not ratified the amendment before the deadline. The Virginia Senate voted in February 2015 to ratify the ERA, leaving the matter to the Virginia House of Delegates.