The 1911 might be the "Iconic" American gun, but if you are just looking at it from a standpoint of what gun you are most likely to see on a day to day basis TODAY it would be the Glock.
The same can be said for Toyota but who would ever think of calling a Camry an iconic American car?
The Colt SAA (and its predecessors) were used by thousands of American soldiers on both sides of the Civil War, carried for protection by an unending stream of citizens moving westward to settle a continent as well as the soldiers sent to protect them. Consider also the Western, no matter who the good guys and villains were you can be sure they'd blast away (without reloading) at each other with the good old SAA. As a final note it continues to be found in plastic form with an orange tip in the aisle of any store where toys may be found.
I don't think Glock's resume even comes close.