Women first organized and collectively fought for suffrage at the national level in July of 1848. Suffragists such as Elizabeth Cady Stanton and Lucretia Mott convened a meeting of over 300 people in Seneca Falls, New York. In the following decades, women marched, protested, lobbied, and even went to jail. By the 1870s, women pressured Congress to vote on an amendment that would recognize their suffrage rights. This amendment became known as the 19th Amendment.
After decades of arguments for and against women's suffrage, Congress finally voted in favor of the 19th Amendment in 1919. This is called ratification. After Congress ratified the 19th Amendment, at least 36 states needed to vote in favor of it for it to become law.
On June 24, 1919, Pennsylvania voted in favor of the Nineteenth Amendment. By August of 1920, 36 states (including Pennsylvania) approved the Amendment, making women’s suffrage legal all across the country.