In 1869 Wyoming extended suffrage to women, at least partially in an attempt to garner enough voters to be admitted as a state. It was admitted to the Union on July 10, 1890.
In addition to being the first U.S. state to extend suffrage to women, Wyoming was also the home of many other firsts for U.S. women in politics. It had the first female court bailiff and the first female justice of the peace in the country. Wyoming was also the first state in the Union to elect a woman governor, Nellie Tayloe Ross in 1925. A List of Wyoming Governors is available.