[3] Aside from a few original sheds and summer cottages,[4] the main feature left in the settlement is the McCahan Memorial Chapel, built in 1930 and closed in 1966.

[5] The first white settlement on the site was a gold placer mining camp established alongside Castle Creek in 1876, which the settlers called Sitting Bull after the Lakota chief.

[4] Although some miners redirected their efforts to Deadwood, the camp maintained a steady population; by 1879, about 100 people lived in Sitting Bull.

Some authors speculate that the settlers supposed that the local Native Americans believed the surrounding area to be full of mystery.

[9] This system had a capacity of 55,000 yards (50 km) of material per month, but the cost far exceeded its returns and within a year, the dredge had been removed and relocated to Oregon.

[5] The Rapid City Daily Journal describes the president and his wife visiting the summer home of former Nebraska Governor Samuel Roy McKelvie by way of Mystic on July 23.

[11] The Coolidges arrived in town on the Crouch Line before departing for the McKelvie cottage and were driven part of the way by George Frink in his lumber wagon.

[15][7] The Burlington rail line closed in November 1983 and today forms part of the George S. Mickelson Trail.

[4] On August 1, 1986, 43 acres (17 ha) of the original townsite were added to the National Register of Historic Places; however, the exact area and details of contributing properties are restricted.