Nominations were announced Tuesday.
Williams' latest album, "West," is nominated for album of the year. The track "Are You Alright?" is nominated for song of the year, and Williams is nominated for artist of the year.
Griffin is nominated for album of the year for "Children Running Through," song of the year for "Heavenly Day" and artist of the year.
The Avett Brothers are nominated for album of the year for "Emotionalism," new and emerging artist and duo group of the year.
Other artists receiving nominations include Bob Dylan for his album "Modern Times," Sam Bush and Buddy Miller for instrumentalist of the year, and Son Volt and Old Crow Medicine Show for duo group of the year.
"The nominations reflect the diversity and ever-growing popularity of Americana music," said Jed Hilly, executive director of the Americana Music Association.
The awards will be presented Nov. 1 at the Ryman Auditorium. The loose genre can be described as American roots music, with influences of country, blues, rock 'n' roll, bluegrass and folk, among others.