Mount Rushmore National Memorial - Keystone, SD - Smithsonian Art Inventory Sculptures on Waymarking.com

County of art: Pennington County
Location of art: 3 miles W. of Keystone on SD 244, W. of US 16
Artist: Gutzon Borglum, 1867-1941, sculptor & Lincoln Borglum, 1912-1986, assistant sculptor
Date of art: began in 1927 stopped work October 1941

Remarks:
"Work on the monument began August 10, 1927, the day President Calvin Coolidge dedicated Mount Rushmore. Fourteen years were needed to bring the sculpture to its conclusion, but because of bad weather and lack of funds only six years were actually spent in the carving. Work was suspended October 31, 1941. The idea for carving the monument was conceived by Doane Robinson, the South Dakota State Historian in 1923. His original idea was to carve romantic western heroes. 361 local hard rock miners assisted in creating the work. Total cost of the memorial was $989,992, of which $836,000 was federally funded. The mountain is named after Charles E. Rushmore, a New York lawyer who researched the land claims of miners in the 1880s. In 1927, he gave Borglum the first $5,000 for the memorial. After Borglum's death, his son Lincoln Borglum worked with the crew to finish the job." ~ Smithsonian American Art Museum

All kinds of details and history can be read in many sources. I will provided a few:
Wikipedia   National Park Service   South Dakota Attractions   Black Hills Badlands   Trip Advisor

"South Dakota historian Doane Robinson is credited with conceiving the idea of carving the likenesses of famous people into the Black Hills region of South Dakota in order to promote tourism in the region. Robinson's initial idea was to sculpt the Needles; however, Gutzon Borglum rejected the Needles site because of the poor quality of the granite and strong opposition from Native American groups. They settled on the Mount Rushmore location, which also has the advantage of facing southeast for maximum sun exposure. Robinson wanted it to feature western heroes like Lewis and Clark, Red Cloud, and Buffalo Bill Cody, but Borglum decided the sculpture should have a more national focus and chose the four presidents whose likenesses would be carved into the mountain. After securing federal funding through the enthusiastic sponsorship of "Mount Rushmore's great political patron", U.S. Senator Peter Norbeck, construction on the memorial began in 1927, and the presidents' faces were completed between 1934 and 1939. Upon Gutzon Borglum's death in March 1941, his son Lincoln Borglum took over construction. Although the initial concept called for each president to be depicted from head to waist, lack of funding forced construction to end in late October 1941." ~ Wikipedia