1. Colorado became a state: On April 5, 1876, Colorado was admitted as the 38th state in the Union. The Colorado State Capitol building was completed in 1908 and is a prominent feature in downtown Denver.

2. The first legal bets on horse racing: In 1949, a bill was passed to allow legal pari-mutuel betting on horse racing in Colorado. On April 5th of that year, the first legal bets on horse racing were placed at the Arapahoe Park racetrack.

3. Denver International Airport opened: On April 5, 1995, the new Denver International Airport opened its doors. The airport was built on a 34,000-acre site east of Denver and is one of the largest airports in the world.

4. The Ludlow Massacre: On April 5, 1914, the Colorado National Guard attacked a tent colony of striking mine workers at Ludlow, Colorado. The attack resulted in the deaths of 20 people, including 11 children.

5. Colorado Rockies inaugural game: On April 5, 1993, the Colorado Rockies played their first-ever Major League Baseball game. The Rockies defeated the New York Mets, 11-9, in front of a sellout crowd at Mile High Stadium.