1. The Pike's Peak Gold Rush: On July 21, 1858, the discovery of gold in the streams of Pike's Peak in Colorado sparked the Pike's Peak Gold Rush. This led to a surge of people migrating to Colorado in search of the precious metal.

2. The founding of Summit County: On July 21, 1861, Summit County was founded. The county was named after the mountain range, and its economy was largely driven by mining.

3. The establishment of Rocky Mountain National Park: On July 21, 1915, Rocky Mountain National Park was established. The park is home to majestic mountains, alpine lakes, and diverse wildlife, attracting millions of visitors every year.

4. The birth of astronaut Jack Lousma: On July 21, 1936, astronaut Jack Lousma was born in Grand Rapids, Michigan. He later moved to Colorado and attended the University of Colorado Boulder before eventually joining NASA.

5. The legalization of marijuana: On July 21, 2014, Colorado became the first state in the US to legalize the recreational use of marijuana. The move sparked a nationwide debate on drug policy and contributed to a growing industry for marijuana-based products in the state.