1. The opening of the U.S. Air Force Academy: On October 3, 1955, the United States Air Force Academy officially opened its doors in Colorado Springs. Since then, the academy has been a vital institution in the U.S. military, training and preparing young men and women for leadership roles within the Air Force.

2. The founding of the city of Denver: On October 3, 1858, a group of settlers led by William Larimer Jr. founded the city of Denver. Initially named "Denver City" after the then-governor of Kansas Territory, the city has since grown into a vibrant metropolis and one of the fastest-growing cities in the United States.

3. The completion of the Eisenhower Tunnel: On October 3, 1973, the Eisenhower Tunnel was completed after eight years of construction. At over 1.7 miles in length, the tunnel is one of the longest in North America and serves as a vital link between Denver and the ski resorts of Summit County.

4. The deadliest avalanche in U.S. history: On October 3, 1913, an avalanche struck near the town of Wellington, Colorado, killing 96 people. The disaster, known as the Wellington Avalanche, was caused by record snowfall and blizzard conditions.

5. The Colorado Rockies make postseason history: On October 3, 1995, the Colorado Rockies played their first home playoff game at Mile High Stadium. The Rockies went on to win the game 7-5, becoming the first National League team to win in their inaugural playoff appearance. The Rockies would go on to make it all the way to the World Series that year, ultimately falling to the Cleveland Indians.