1. On September 19, 1909, the state of Colorado established the Colorado State Fair in Pueblo, which has been held annually ever since. The fair showcases Colorado agriculture, livestock, and other industries, as well as carnival rides, food, and entertainment.

2. In 1945, the Rocky Mountain Arsenal, a chemical weapons manufacturing site located near Denver, Colorado, began operation on September 19. The arsenal produced nerve agents, such as Sarin and VX, and other chemical weapons until its closure in 1992.

3. On September 19, 2005, the Colorado Rockies played their final game at Denver's original ballpark, Coors Field, before moving to their current home, Coors Field II. The team had played at Coors Field since its opening in 1995.

4. In 2013, on September 19, the catastrophic floods in Colorado intensified, resulting in widespread damage and loss of life. The disaster affected 24 counties and caused more than $2 billion in damages.

5. On September 19, 1910, Colorado Springs patriarch Spencer Penrose opened the luxurious Broadmoor Hotel. The hotel has since been a popular destination for visitors to the Colorado Springs area, and it has undergone several renovations and expansions over the years.