1. On December 18, 1867, Wyoming became a territory of the United States. This was a significant milestone in Wyoming's history, as it paved the way for statehood in the future.

2. In 1886, the University of Wyoming was founded in Laramie. This institution has played a crucial role in the educational development of Wyoming and has produced many notable graduates over the years.

3. On December 18, 1922, the Cheyenne Frontiera Days Rodeo Association was officially organized. This annual event is considered to be one of the largest outdoor rodeos in the world and is a major tourist attraction for Wyoming.

4. In 1971, Bill Clinton, who would later become the 42nd President of the United States, was married to his first wife, Hillary Rodham, in Fayetteville, Arkansas. This event is significant for Wyoming history because it was at this time that the Clintons began their political careers, which would eventually bring them to Wyoming during their presidential campaigns.

5. On December 18, 2009, President Barack Obama signed into law the Omnibus Public Lands Management Act of 2009. This legislation provided increased protections for many of Wyoming's natural resources, including public lands, rivers, and wildlife habitats. It was a major victory for conservation efforts in the state.