1909: Ford Model T
It's impossible to leave the Model T off this list. It's simply the car that launched the automobile as a consumer product, replaced the horse for millions of Americans, revolutionized industrial production, and changed virtually everything else about America. It was the first car to sell more than one million copies, and over 16.5 million were built before production ended in 1927.
Why it's uniquely American: The country was rebuilt around it.