South Dakota Facts

Mount Rushmore has a secret: a 70-foot granite tunnel cut directly behind the faces. Sculptor Gutzon Borglum began drilling it in 1938 to house America's founding documents for future civilizations. Congress shut the project down in 1939 and Borglum died in 1941. In 1998, his family lowered 16 porcelain panels into a titanium vault and sealed it under a 1,200-pound granite capstone. Nobody can go inside.

Luigi Del Bianco immigrated from Italy as a teenager, already trained as a stone carver. Sculptor Gutzon Borglum named him Chief Carver of Mount Rushmore in 1935. He was the one man trusted to finish all four presidents' faces. Del Bianco carved the twinkle in Lincoln's eyes and shaped Jefferson's lips. Borglum called him worth any three men in America. An Italian immigrant gave the presidents their faces.

Sturgis, South Dakota has 7,000 residents and hosts the world's biggest motorcycle rally, which drew a record 739,000 riders in 2015. It began in 1938 with nine riders racing for a crowd under 200. Pappy Hoel had just opened an Indian Motorcycle shop and formed the Jackpine Gypsies. His wife Pearl counted the bikes the night before and cooked a picnic for every rider. She kept doing it until the 1950s, when the crowd outgrew her kitchen.

Sue, the T. rex at Chicago's Field Museum, was found because of a flat tire. In 1990, a South Dakota fossil crew drove into town to fix it, but Sue Hendrickson stayed behind and walked her dog to cliffs the crew had not checked. Giant bones jutted from the rock above her, part of one of the most complete T. rex skeletons ever found. The skeleton still carries her name.