The current location of Interstate Highway 90, and the resulting importance of Piedmont Valley and Summerset, have deep historical roots. Piedmont Valley was a route that the Native Americans used hundreds of years earlier. Later, the early pioneers established pack trails through Piedmont Valley. In 1857-58 Lieutenant G.K Warren was dispatched from Fort Laramie and given the responsibility of exploring the Black Hills and perimeter areas – including the Piedmont Valley area. After a thorough assessment, Warren reported that the valleys between the ridge and the higher Black Hills provided excellent possibilities for road routes. This finding hastened further development and the existing pack trails later became stage and wagon roads. Stage and wagon routes later became gravel roads. Finally, gravel roads became paved roadways and finally an Interstate Highway was built. The importance of this transportation route is evidenced by the fact that this was the first section of Interstate highway to be built in South Dakota (in 1958).
After the Warren Expedition, the importance of the area around present-day Summerset was furthered by the Custer Expedition in 1874. General George A. Custer left Fort Lincoln near Bismarck, ND and set out to map the Black Hills and collect useful information. One accomplishment of the Custer Expedition was the development of a wagon route from the higher Black Hills down into the Piedmont Valley. This route was developed just north of where present-day Black Hawk is located now. The route became important in the future as other settlers and prospectors utilized it to gain access to the Black Hills. Custer also explored the entire area from present-day Piedmont to Bear Butte and reported on the area’s favorable climate and rich natural resources, including gold.
When the Black Hills gold rush started, the area was officially opened to settlement by the U.S. Government. This created the need for better transportation routes to afford passage of people, goods and equipment. One of the more important trails and stage routes that was developed included the Sidney-Deadwood Stage Road which ran through the Piedmont Valley between Rapid City and Sturgis and then connected to Deadwood. This route was regularly used by 1878 and was located roughly where the present day Highway 79 service road is now.
The regional importance of this area increased in 1897 when the first railroad was developed through the area. The Fremont Elkhorn and Missouri Valley Railroad (aka the “Elkhorn”) was extended from Rapid City north through the Piedmont Valley to Whitewood. This resulted in a dramatic decrease in wagon transport in the area and a dramatic influx of settlers. Area development was enhanced by the connection of Homestake Mining Company’s narrow-gauge railroad line to the Elkhorn line. The community of Piedmont was platted by Homestake Mining Co. in 1890 and was created for the purpose of providing housing and commerce for the mine’s workers and families.
The decreasing influence of the gold industry and the railroads over the years resulted in a general decline in the Piedmont Valley in the first half of the 1900’s. But this decline was reversed with the construction of improved roadways. As in other areas of the country, the largest recent impact to the Piedmont Valley and the area where present-day Summerset is located, was the construction of paved roadways and particularly Interstate Highway 90. The construction of I-90 coupled with the growth of Rapid City, resulted in significant residential development in unincorporated areas of Piedmont Valley. Since the 1970’s especially, numerous subdivisions and developments have sprung up and continue to do so. As noted, Summerset itself, owes its role as a bedroom community to the presence of I-90 and the proximity to Rapid City.
The City of Summerset was incorporated in an election held June 7, 2005 and became at that time, and still is now - the State’s newest second class municipality. Summerset Subdivision, which comprises most of the city’s development, was originally platted in 2000 with the first home constructed early in 2001. The incorporated city limits of Summerset currently encompass approximately 1,430 acres.