The tour begins August 11 in Atlanta, with dates stretching into early September, when they'll wrap with a pair of shows at the Historic Mountain Winery in Saratoga, Calif.
The five artists have known each other for some time, having collaborated on albums, shared the stage and covered each other's songs; however, this marks the first time they will work together as a unit.
The set will be varied, featuring ensemble performances, solo numbers and, at times, instrument swapping.
"I always wanted to run away with the traveling circus," Welch commented. "I guess I finally get my chance. Too bad there are no elephants."
Griffin added, "I feel really lucky to be a part of this. Emmylou is so awesome, and all the other members of this tour are truly amazing. Plus, we're all friends."
Harris recently picked up her 11th Grammy award for her collaboration with Welch on the "O Brother, Where Art Thou?" soundtrack. Last year, Harris released her 23rd album, Stumble Into Grace.
Critically acclaimed singer/songwriter Griffin's fourth studio album, Impossible Dream, comes out April 20. Her songs have been covered by the Dixie Chicks, Bette Midler and Mary Chapin Carpenter.
Miller started off doing session work and soon became the lead guitarist in Harris' band. As a solo artist, he's won his own legion of fans, blending soulful Americana with blues-tinted country and dusty rock ‘n' roll.
Welch and Rawlings have been writing, recording and performing together since their college days. Rawlings produced Welch's latest effort, Soul Journey, released last June.