Hmmmm, can't vote for Charles Baggage or Alan Turing since they were British. So, I'll vote for Jack Kilby. Who? you may ask. Search for his name and consider what life would be today without his invention.
There are too many great Americans that have contributed to this great nation. Some from the beginning and others, more recently. I'm sorry but I can't choose just one. Not sure I could pick 10 either.
It's not that he was successful. In fact he never succeeded in anything. What makes him so important is that he TRIED to do what he believed in but the system wouldn't let him. All his contemporaries did what was best for themselves.
I'm with @lordmarcovan - Ben Franklin IMO, did more for this country and most of the world with his inventions and knowledge. Lincoln would be my close second, and then Edison. Great thread BTW.
God bless ol' Fred Rogers. He was the real deal. I remember watching a TV prank show where they'd set up in a hotel, with the by-then-elderly Mr. Rogers as the intended prankee. They tried various "Candid Camera" style ruses to get him mad. (The show might've even been the later version of Candid Camera itself - I forget.) Anyway, their attempts to get his goat all failed spectacularly, because Fred Rogers was so good-natured and unflappable. For instance, when informed that his room had a broken or missing TV set, Mr. Rogers smiled and replied that it was no problem at all - he'd already had plenty enough television in his life.
Teddy Roosevelt has always been a favorite of mine . He's always showed to me how much he truly love this country . As a president , as a naturalist. We wouldn't have the national parks if not for love of nature and the beauty of this country . If he was alive today no one would every disrespect the natural beauty of this nation.
Edison would definitely have made my short list had it not been for a few less-savory personal traits, and animal cruelty in his experiments (In one documentary I saw - without warning - film footage of a kitten being deliberately electrocuted to death, which disturbs me to this day.) But his inventions rightly earn him immortality.
Teddy Roosevelt was a great American, no doubt, and deserves the gratitude of numismatists, but he was also a borderline madman whose sociopathic/violent tendencies were more than a little frightening. (And he loved to kill animals, too.) Still, he was American to the core and deserving of his glory. Thinking of TR reminds me of someone we lost in the last few years who once played TR in a movie. Late-great funnyman Robin Williams had his flaws and his demons, too, but he was another American original, and I miss him.
I'd have to put Thomas Jefferson up against Ben Franklin as a near equivalent, but I think it unlikely that any one human being has had greater individual impact upon the rest of humanity than Thomas Alva Edison.
Yes, I already mentioned how Edison's less-savory side kept him from being my choice, despite his obvious importance.