Rock shelters in the canyon date back as far as 5,000 years. Reliable water and south-facing shelters would have made harsh, ancient winters tolerable for early North Americans. The tradition of wintering in the canyon continued under indigenous tribes. Archaeological finds suggest the Jicarilla Apache occupied eastern Colorado from around 1200 to 1750 CE. The Comanche and Mouache Ute, among others, controlled parts of the region during this period as well.

• 1858: Gold is discovered at Dry Creek, and what is known as the “gold rush” ensues. State Highway 83, just outside the canyon, follows one of the oldest stagecoach lines in Colorado. This route linked both the Smoky Hill and Santa Fe trails to the goldfields outside of Denver. 
• 1864: U.S. Army Volunteers make four unprovoked attacks on Cheyenne villages in the area, beginning a summer of violence. The grave of one local resident killed in a September skirmish, Conrad Moschel, is visible just outside the modern park boundary along Castlewood Canyon Road. 
• 1890: Castlewood Dam is built in Castlewood Canyon in an attempt to transform the flood-prone Cherry Creek into a reliable irrigation source. 
• 1894: 160 acres at the foot of Wildcat Canyon are purchased by Patrick and Margaret Lucas. The couple meet after immigrating from Ireland to Arizona and marry in 1889 before moving to Colorado. The Lucas children and grandchildren keep up the property until a fire burns the structure in the early 1960s. Even as a ruin, the Lucas Homestead remains a feature of the park.
• 1933: Notorious for frequent leaks, the Castlewood Dam bursts on the night of August 3, 1933. A wall of water sends building materials, timber, cattle, cars and debris tumbling toward Denver. The city remains flooded for several days. Remains of the dam can be seen in the park today.
• 1961: Lawrence P. Brown, a descendant of Margaret and Patrick Lucas, sells 87 acres of his family’s old homestead to the newly created state park system for $10. 
• 1964: Castlewood Canyon becomes a state park. 
• 1970s: The park expands 792 acres to include the former dam and reservoir.
• 2002: The park purchases the remaining 73 acres of the Lucas homestead from the Metzler family. Total land now sits at a little over 2,500 acres. 
• 2020: Castlewood Canyon State Park officially becomes a Leave No Trace Gold Standard site. Hikers and rock climbers should “pack in, pack out” the 10 Essentials, and all visitors are encouraged to practice Leave No Trace on the trail.