1. On August 28, 1864, the infamous Sand Creek Massacre took place in southeastern Colorado, when a group of Colorado volunteer soldiers attacked and killed over 150 Cheyenne and Arapaho people, mostly women, children, and elderly. The massacre sparked outrage and led to congressional investigations and reforms in Indian policy.

2. On August 28, 1923, the Town of Dillon in Summit County was incorporated. The town, located along I-70 and near several ski resorts, is now a popular destination for outdoor activities and events.

3. On August 28, 1968, the Democratic National Convention began in Chicago. Colorado Senator and presidential candidate Eugene McCarthy was among the contenders, and Colorado delegates were split between him and Vice President Hubert Humphrey. The convention was marked by protests and police violence, and Humphrey ultimately won the nomination.

4. On August 28, 1973, the Arapahoe County Fairgrounds and Regional Park opened in Aurora, providing a venue for agricultural shows, rodeos, concerts, and other events. The park has since expanded and features several amenities, including a golf course, playgrounds, and trails.

5. On August 28, 1993, Mark Wellman became the first paraplegic to climb the Diamond on Longs Peak, one of Colorado's most challenging peaks. Wellman, a former Olympic skier and rock climber, used a specially designed wheelchair and rope system to complete the climb.