Signs marking the entrance to the Pine Ridge Indian Reservation in South Dakota make it clear when you're literally "off the reservation," but the figurative meaning of the phrase has shifted over time. Kristi Eaton/AP hide caption

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The Star-Spangled Banner — the flag that inspired our National Anthem — on display at the Smithsonian's National Museum of American History. Hugh Talman/Courtesy of the Smithsonian's National Museum of American History hide caption

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The sun rises behind the cosmic microwave background (CMB) radiation telescopes at the National Science Foundation'€™s South Pole Station. Steffen Richter/Harvard University hide caption

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Wisconsin's Traevon Jackson at practice for the 2014 NCAA men's college basketball tournament. Commentator Frank Deford says that, despite NCAA claims to the contrary, most college players are not typical students — "their job is to play a sport." Jae C. Hong/AP hide caption

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