1. On December 3, 1919, Colorado became the 22nd state to ratify the 19th Amendment, which granted women the right to vote.

2. In 1949, the first Vail ski resort opened on December 3rd. Today, Vail is one of the top ski destinations in the world, attracting millions of visitors each year.

3. On December 3, 1973, the final episode of the popular television series "Bonanza" aired. The show, which was set in the fictional town of Virginia City, Nevada, featured the exploits of the Cartwright family, who were cattle ranchers and landowners in the Old West.

4. In 1997, the Stapleton International Airport in Denver closed on December 3rd. It was replaced by the new Denver International Airport, which was built in a location farther outside of the city and is now one of the busiest airports in the world.

5. December 3rd, 2012 marked the first day of legalized recreational marijuana sales in Colorado, making it the first state in the US to allow the sale, possession, and use of the drug for recreational purposes. This move helped to establish Colorado as a pioneer in the nationwide trend towards the legalization of marijuana.