Did you know that December 10, which is Sunday this year, is known as Wyoming Day?

According to the Library of Congress, on December 10, 1869, John Campbell, who was the governor of the Wyoming Territory, approved the first law in U.S. history that explicitly granted women the right to vote.

The events leading up to the introduction and passage of the suffrage law are a little unclear though. One popular story credits Esther Hobart Morris with the law’s success. Morris would go on to be the first female justice of the peace. The story goes that she arrived in South Pass just before the 1869 elections and decided to hold a tea party to present her support of woman suffrage to legislative candidates. Democrat William H. Bright was supposedly there that night and when he won a seat in the legislature, he introduced a bill granting women the right to vote. Many of the legislators treated it as a joke, but they passed it nonetheless. They were therefore surprised when Governor Campbell signed it into law.

While there are several other “Wyoming Days,” December 10 gained the distinction in honor of that historic leap forward for women’s rights.