1. In 1864, the Sand Creek massacre took place in Colorado. A group of Colorado militia attacked a peaceful camp of Cheyenne and Arapaho tribes, killing over 150 people, mostly women, children, and the elderly.

2. In 1878, Colorado held its first election following statehood. The Republican Party won, with Frederick Pitkin becoming the state's second governor.

3. In 1934, a record-breaking snowstorm began in Colorado. Over three feet of snow fell in some areas, and the storm caused widespread power outages and transportation disruptions.

4. In 1975, a United Airlines flight departing from Denver crashed shortly after takeoff, killing all 44 people on board. The cause of the accident was determined to be a malfunctioning engine.

5. In 2010, a natural gas explosion occurred in the town of Frederick, Colorado. Two people were killed and several others injured, and the blast destroyed several homes and buildings in the area.