1. The first game of Wyoming Cowboys football occurred on September 3, 1892, against the Cheyenne Athletic Club. Wyoming won 12-0, and it marks the start of a long and storied football program at the University of Wyoming.

2. On September 3, 1938, the first annual Sugar Beet Day was held in Lovell, Wyoming. It was a celebration of the region's agriculture and focused on the sugar beet industry, which was a significant economic force in the area at the time.

3. In 1954, the first ever Wyoming State Fair was held in Douglas, Wyoming, on September 3. The fair is still held annually to this day and is a celebration of Wyoming's agricultural heritage and culture.

4. September 3, 1972, saw the opening of the Casper Planetarium in Casper, Wyoming. The planetarium has since become a beloved institution in the state and is a popular destination for both locals and visitors.

5. The Wyoming Army National Guard was activated on September 3, 1940, as part of the mobilization for World War II. The guard served in several theaters of the war and has continued to serve the state and the nation in various capacities throughout its history.