Most Influential American Musician of All Time?

There is no 'greatest'.

There are people who define an era or particular kind of music.

Analogtroll beat me to the naming of one: Woodrow Wilson (Woody) Guthrie.

Then, of course there are the big-time commercial successes like Bernstien and Gershwin and Armstrong.

Someone mentioned the Beatles...which are, of course one of many British Bands that introduced White America to The Blues.

Thank you, everybody for leaving Irving Berlin out of it.

Ah, let the controversy roll....(and rock!)

Frank Zappa.

Bill Monroe - perhaps the only undisputed creator of a genre of music and who is in the bluegrass, country and rock n roll halls of fame. Honorable mentions - Jimmie Rodgers and Les Paul.

Here is how I would break it down:

Country: The Carter Family
Folk/Rock: Dylan
Jazz: Armstrong
Classical: Solti

Frank Zappa was the most gifted musician in the last 100 years, maybe more. He wrote and played music that very very few people would ever attempt, let alone do a credible job. RIP Frank...