I was just alerted to Venus magazine's publication of a "greatest female guitarists of all time" list. Of course, I'm always excited to see women get the credit they deserve. But Venus' panel of judges left off a woman I would argue to be the most influential American guitarist of all time: Mother Maybelle Carter.
Mother Maybelle, founding member of the Carter Family, gets very little credit for what she did. This could be, in part, because of how modest she was. But it could also be because of how commonplace her style became over the years. Her approach to guitar was called "scratch", and it involved using her thumb to pluck out the melody on the bass lines while strumming the high notes with the rest of her fingers.
In addition to Tennessee Ernie Ford, Doc Watson, and Norman Blake, this style has been employed by damn near everyone who first picks up an acoustic guitar. Not only was she a great player, she influenced almost every man and woman in the room.