The amendment was passed by U.S. lawmakers in 1972 and the heads of 35 states have subsequently ratified it, but three more states must support it before it can become part of the U.S. Constitution.

Streep is now pushing for a revival of the amendment, insisting the time is right to secure equal rights for women under the law.

She writes, "I am writing to ask you to stand up for equality - for your mother, your daughter, your sister, your wife or yourself - by actively supporting the Equal Rights Amendment.

"A whole new generation of women and girls are talking about equality - equal pay, equal protection from sexual assault, equal rights."

The 66 year old's activism has poured into her career as well - she is portraying British women's rights icon Emeline Pankhurst in her latest film Suffragette. As the leader of the British suffragette movement, Pankhurst helped women win the right to vote.