Stretching north from Sheridan for about 15 miles, the Black Diamond Trail highlights Sheridan County mining districts that were integral to the settlement and development of the city and county of Sheridan. Although the peak of activity was the 1910s and early 1920s, commercial mining took place here from the 1890s through the 1990s, and mining communities existed here until 1977. However, even today the boom and bust cycle continues as planning for new mining in the area started once again in 2012.