1. On December 23, 1913, the Denver & Rio Grande Railroad opened the Moffat Tunnel. The project had taken six years to complete and was seen as a major engineering achievement, as it completed a rail link between Denver and Salt Lake City.

2. December 23, 1982, marked the day the Denver Broncos clinched their first AFC West division title. The team went on to secure a spot in Super Bowl XVII, where they lost to the Washington Redskins.

3. In 2006, on December 23, Denver Mayor John Hickenlooper announced that the city would be hosting the 2008 Democratic National Convention. The event would later bring thousands of visitors to Denver and solidify its status as a political hub.

4. On December 23, 2015, the Colorado Springs Gazette reported that a previously undisclosed military unit was based at Fort Carson. The unit, which was described as an intelligence gathering outfit, had been operating in Iraq and Afghanistan for several years.

5. December 23, 2018, marked the day that Colorado’s new police accountability law went into effect. The law, which was passed in the wake of nationwide protests against police brutality, required law enforcement agencies to adopt new use-of-force policies and to collect more data on police interactions with the public.