Abraham Lincoln, who invented a hydraulic device for lifting ships over shoals, was the only US president ever granted a patent.

According to the Gemological Institute of America, up until the 1730's, India was the only source for diamonds in the world.

Antarctica is the only continent without reptiles or snakes.

Australia is the only country that is also a continent.

Baskin Robbins once made ketchup ice cream. This was the only vegetable flavored ice cream produced.

Bats are the only mammal that can fly.

Bats have only one baby a year.

Elvis Presley made only one television commercial - an ad for "Southern Maid Doughnuts" that ran in 1954.

Franklin D. Roosevelt was the only US president elected four times.

George Washington is the only man whose birthday is a legal holiday in every state of the United States.

Gerald Ford was the only US president not to have been elected to either the presidency or the vice presidency.

Giraffes are the only animals born with horns. Both males and females are born with bony knobs on the forehead.

Grover Cleveland is the only US president to have been married in the White House.

Hawaii has the only royal palace in the United States - Iolani.

Hawaii is the only US state that grows coffee.

Honey is the only food that does not spoil. Honey found in the tombs of Egyptian pharaohs has been tasted by archaeologists and found edible.

In 1969, "Midnight Cowboy" became the first and only X-rated production to win the Academy Award for Best Picture. (Its rating has since been changed to R.)

James Buchanan was the only US president never to be married.

Libra, the Scales, is the only inanimate symbol in the zodiac.

Maine is the only state in the United States whose name is just one syllable.

Mercury is the only metal that is liquid at room temperature.

Notables who were the only child in their families include Ansel Adams, Hans Christian Andersen, Carol Burnett, Raymond Chandler, Eric Clapton, Linda Ellerbee, Louis Gossett, Jr., Robert Englund, Charlton Heston, James Earl Jones, Ted Koppel, Ivan Lendl, Barry Manilow, Maria Montessori, Jack Nicholson, Flannery O'Connor, Al Pacino, Charlie "Bird" Parker, Robert Edwin Peary, Lisa Marie Presley, Pres. Franklin D. Roosevelt, Jean-Paul Sartre, Frank Sinatra, Robin Williams, and Tiger Woods.

Only one foreign country--Liberia in Africa--has a capital city named after an American president. The capital is Monrovia, named after James Monroe.

Only one person ever won an Oscar by a write-in. In 1934 and 1935, write-in votes were permitted and Hal Mohr won an Oscar for Cinematography in 1935 for his work on "A Midsummer Night's Dream" as a write-in. 1935 was the last year such votes were permitted.

Q is the only letter in the alphabet that does not appear in the name of any state of the United States.

Richard M. Nixon is the only US president to have resigned.

Swans are the only birds with penises.

Teeth are the only parts of the human body that can't repair themselves.

The bat is the only mammal that can fly.

The Beatles held the Top Five spots on the April 4th, 1964 Billboard singles chart. To date, they're the only band that has ever accomplished that.

The Bledowska Desert in Poland is the only true desert in Europe.

The bloodhound is the only animal whose evidence is admissible in an American court.

The city of Chicago has the only post office in the world where you can drive your car through.

The first graves in Arlington National Cemetery were dug by James Parks, a former Arlington Estate slave. Buried in Section 15, James Parks is the only person buried in Arlington National Cemetery who was also born on the property.

The hummingbird is the only bird that can fly backwards.

The hyoid bone in the throat is the only bone in the human body not joined to another.

The king of hearts is the only king without a moustache on a standard playing card.

The number 4 is the only number in the English language that has the same number of letters in its name as its meaning.

The only active diamond mine in the United States is in Arkansas.

The only continent without reptiles or snakes is Antarctica.

The only country in the world that has a Bill of Rights for Cows is India.

The only crime defined in the U.S. Constitution is treason - Article III, Section 3.

The only Englishman to become Pope was Nicholas Breakspear, who was Adrian IV from 1154 to 1159.

The only father and son to hit back-to-back home runs in a major league baseball game? Ken Griffey, Jr., and his father, Ken Griffey, Sr., both of the Seattle Mariners, in a game against the California Angels on September 14, 1990.

The only known common metal that is liquid at room temperature is mercury.

The only lizard that has a voice is the Gecko.

The only married couple to fly together in space were Jan Davis and Mark Lee, who flew aboard the Endeavor space shuttle from Sept 12-20, 1992.

The only one of his sculptures that Michelangelo signed was the "The Pieta," completed in 1500.

The only part of the human body that has no blood supply is the cornea in the eye. It takes in oxygen directly from the air.

The only repealed amendment to the US Constitution deals with the prohibition of alcohol.

The only river that flows both north and south of the equator is the Congo. It crosses the equator twice.

The only rock that floats in water is pumice.

The only wood used by famed London cabinetmaker Thomas Chippendale was mahogany.

The pecan tree is the only naturally growing nut tree in North American. It is native to the Texas, Mississippi and Mexico River Valleys.

The penguin is the only bird that can swim, but not fly. It is also the only bird that walks upright.

The Virginia opossum is the only marsupial (pouched mammal) indigenous to North America.

There is only one Q in a Scrabble game.

There's only one city in the United States named merely "Beach." It is found in North Dakota, which is a land-locked state.

Uranus is the only planet that rotates on its side.

When Pierre Trudeau wed Margaret Sinclair in 1971 he became the only Canadian Prime Minister to get married while in office. The couple divorced in 1984.

Woodrow Wilson was the only US president to earn a doctorate.

Zsa Zsa Gabor was the first - and only - recipient of a Golden Globe Award for "Most Glamorous Actress." She won the peculiar award in 1958. The category was deleted thereafter.