In the running for the prize are eight US presidents, two legendary civil rights activists, several of the most famous innovators in history and -- a talk-show host.
After Britain opted for Winston Churchill and the French plumped for Charles de Gaulle, the US has been asked to choose the greatest American ever.
The list, whittled down from 100 to 25 on Sunday night, includes the obvious suspects, from Abraham Lincoln to Martin Luther King and John Kennedy. But it also contains some names that are likely to raise a few eyebrows, including Oprah Winfrey, the doyenne of daytime TV, and Billy Graham, the evangelist. Walt Disney, the creator of Mickey Mouse and Donald Duck, two of America's most successful and iconic cultural exports, is also in the running.
President George W. Bush and predecessor Bill Clinton make the shortlist, along with the astronaut Neil Armstrong, the Microsoft billionaire Bill Gates, and the inventors of the airplane, Orville and Wilbur Wright.
However, a spokeswoman for the Discovery Channel, which is broadcasting the four-part series, refused to reveal who was leading the field.
"The conversation is just beginning," she said on Monday.
But the smart money is on Lincoln, the first Republican president, who abolished slavery and guided the country through the civil war, or King, the assassinated civil rights leader who sparked the country's conscience over race relations.
Those who appeared in the top 100 list but fell by the wayside at the first hurdle included Hugh Hefner, the founder of Playboy magazine, the pop star Madonna and Michael Jackson.
The full rundown, which was voted for by more than half a million people, and was evidence, some cultural commentators said, of the continued dumbing down of America.
* Muhammad Ali, Neil Armstrong, Lance Armstrong, George W Bush, Bill Clinton, Walt Disney, Albert Einstein, Henry Ford, Benmjamin Franklin, Billy Graham, Bob Hope
* Thomas Jefferson, John F. Kennedy, Martin Luther King, Abraham Lincoln, Rosa Parks, Elvis Presley
* Ronald Reagan, Eleanor Roosevelt, Franklin D Roosevelt, George Washington, Oprah Winfrey, the Wright brothers
Source: The Guardian
In a change from the European format, under which a celebrity or academic championed a chosen contender, the US version uses a panel of celebrities to discuss the nominees' assets.
The public will whittle the remaining contenders down to five, before the live grand finale is broadcast at the end of the month.