1. In 1877, the state of Colorado executed its first death row inmate. John Stoefel was convicted of murdering his wife and two children, and was hanged on June 18th.

2. On June 18, 1881, the Colorado National Guard was formed. Originally known as the Colorado Militia, this group was tasked with maintaining order and protecting against external threats.

3. In 1910, the Colorado Springs and Cripple Creek District Railway began operating a scenic route through the mountains, offering tourists breathtaking views of the Rocky Mountains.

4. On June 18th, 1917, the Colorado coal miners' strike began. The workers were protesting low wages and unsafe working conditions, in what would become one of the most significant labor disputes in the state's history.

5. In 1976, the Colorado Supreme Court ruled in favor of Karen Silkwood, a nuclear plant worker who died under mysterious circumstances. The ruling allowed her estate to receive damages from her employer, and helped establish the legal basis for whistleblowers to come forward with concerns about workplace safety.