Today marks the 90th anniversary of women winning the right to vote in the United States. While some states had allowed women to vote conditionally, it wasn't until the passing of the 19th amendment to the U.S. Constitution on this date in 1920 that women throughout the country could enjoy the same political rights as their male counterparts.

During the 18th and 19th centuries, a few places such as Sweden, France and the colonial Americas had sporadically allowed women to conditionally vote in local elections. In 1893, New Zealand became the first self-governing nation to grant women the right to vote, followed closely by Australia in 1902. The United States, Canada, England and many other countries did not follow suit until shortly after World War I.

Groups such as the National Women's Party and the National American Woman Suffrage Association had worked for years for women's suffrage in the U.S., and slowly some states granted equal voting rights. With the end of World War I the first war in which American women worked in factories and held other jobs while men were overseas a critical mass of women protested and demonstrated for the same political rights as men, leading to Congress passing the 19th amendment in 1919. The amendment stated:

"That the right of citizens of the United States to vote shall not be denied or abridged by the United States, or by any State, on account of sex."

Soon after, several states such as Illinois, Wisconsin and Michigan, quickly ratified the amendment, while others, like Georgia and Alabama, remained staunchly opposed. Thirty-six states were needed to ratify for women to have equal voting rights, and a senator from Tennessee passed the final vote on Aug. 18th, 1920, making Tennessee the last state needed for the amendment to ratify. Women from all states voted in the following presidential election that November.

A host of countries allowed women to vote around that time, and more followed throughout the decades. In 1979, the United Nations declared that all women should have the right to vote, in the Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW).

While today, women in almost all countries enjoy equal voting rights, a few countries that have some form of voting have lagged behind, perhaps most notably, Vatican City and Saudi Arabia.

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