1. On May 2, 1867, the first railroad train arrived in Denver, Colorado. The Denver Pacific Railroad had completed the first transcontinental line through the city, providing a major boost to Denver's economy and paving the way for further expansion in the region.

2. On May 2, 1885, the small town of Leadville, Colorado experienced one of its worst disasters when a massive explosion rocked the nearby Wellington coal mine. Over 35 miners were killed in the blast, which was caused by a buildup of gas in the mine. It remains one of the deadliest mining accidents in Colorado history.

3. On May 2, 1905, the first issue of the Rocky Mountain News was published in Denver, Colorado. The newspaper quickly became a major player in the region's media landscape, and remained in publication until 2009.

4. On May 2, 1951, the University of Colorado Boulder held its first-ever commencement ceremony at its new campus location. The ceremony included just 99 graduates, but marked the beginning of a major expansion period for the university over the following decades.

5. On May 2, 1999, a mass shooting took place at Columbine High School in Littleton, Colorado. The tragic event took the lives of 13 people and injured dozens more, sparking national conversation and debate around gun control and school safety measures. The Columbine shooting remains one of the deadliest school shootings in U.S. history.