Despite various versions of how he came to call a play in a 1971 playoff game, "Nixon's Play" forever will live on in Washington Redskins lore. As the story goes, coach George Allen, having taken the Redskins to the playoffs for the first time in 25 years, received a phone call from Nixon on the eve of the game and ultimately used the president's suggestion for an end-around against the San Francisco 49ers. The play lost 13 yards. The Redskins went on to lose 24-20, and Nixon went on to resign, first as the team's signal-caller and later, in an unrelated move, as president.

In the midst of moves to abolish the game of football (18 deaths had been reported during the 1905 season), Roosevelt personally encouraged reform in football -- a seminal moment in the sport's history. The result of Roosevelt's efforts to eliminate the violent nature of football in 1905 led to two milestone events in the game's history: The formation of the Intercollegiate Athletic Association of the United States -- which is now known as the National Collegiate Athletic Association -- and the forward pass. Dangerous mass formations such as the wedge were also banned, and the distance necessary to attain a first down was extended from five to 10 yards.

Ford was a two-way football star at the University of Michigan in the early 1930s and even played against the Chicago Bears at Soldier Field as a member of a 1935 collegiate all-star team. After his graduation that year, the center/linebacker spurned contract offers from the Detroit Lions and Green Bay Packers, instead choosing to enroll at Yale Law School. During the 1934 season, Ford, according to The Associated Press, "became the only future U.S. president to tackle a future Heisman Trophy winner when he brought down running back Jay Berwanger, who would win the first Heisman the following year."

Ever wonder why they called Reagan the "Gipper"? Before he was the 40th U.S. president, the actor-turned-politician starred as the Fighting Irish's George Gipp in the 1940 film, "Knute Rockne, All American". Reagan himself was given the nickname "Gipper," which lasted throughout his life. The real-life Gipp suffered a throat infection during one of his last games for Notre Dame and died a few weeks later at the age of 25. On his deathbed, Gipp told coach Rockne to tell his players to "just win just one for the Gipper." Reagan later used the famous quote when seeking election as president.

Bush went on the field with former Dallas Cowboys quarterback Roger Staubach before Super Bowl XXXVI in New Orleans, becoming the first president to appear in person for a Super Bowl coin toss. Ronald Reagan participated in the Super Bowl XIX coin toss via satellite from the White House in 1985.

Clinton, an unabashed Arkansas Razorbacks fan, is famous for using football analogies. He once told an Arkansas audience: "When something is really important to us -- like football -- we care about the facts."

Bush's connection to professional football, however marginal, is one that will live in infamy. The future of the free world was nearly changed in January 2002 when the 43rd U.S. president briefly lost consciousness after he choked on a pretzel while watching Sunday football. Bush fell off his couch and received a scrape and a large bruise on his left cheek bone as a result. He later was seen wearing a Band-Aid on his face to cover a cut he received from his glasses. The lesson: "Always chew your pretzels before you swallow," Bush said.

In 2008, Obama was elected president in large part due to his campaign promise for a new major college football playoff system (well, the extent of his playoff stance's impact on his election is debatable, at best). In his first interview as president-elect, the conversation concluded with Obama discussing the importance of a playoff in major college football. Six years later, a playoff system finally came to fruition ... though not the eight-team incarnation that Obama imagined.