The Indigo Girls [ tickets ] have added more shows to their North American tour, which launched in March and is scheduled to stretch into next year.

Since last check, the folk-rock duo has scheduled dates in Alaska, New York, California, Missouri, Oklahoma, Texas and Louisiana. The itinerary includes two-night stands in Atlanta; Anchorage, AK; and Brownfield, ME. Details are listed below.

Emerging singer/songwriter Brandi Carlile [ tickets ], folk-rockers Girlyman [ tickets ] and politically charged soul-rock band Three5Human [ tickets ] will trade off in supporting most of the dates. Information on which acts open specific shows is available at the Indigo Girls' website.

While on the road, the Girls are continuing their activist efforts, playing benefit shows for organizations including Honor the Earth and those that are working to rebuild New Orleans. The band is also making sure the outing is environmentally friendly, offering free tickets to fans who agree to pick up recyclables after shows.

The Indigo Girls are touring behind their 10th studio album, "Despite Our Differences," which surfaced in September. The set, produced by Mitchell Froom (Paul McCartney, Sheryl Crow) is the Grammy-winning duo's first for Hollywood Records. It features guest artists including Carlile and Pink.

"Despite Our Differences" also marks Amy Ray and Emily Saliers' 20th year of performing as the Indigo Girls. As the title would indicate, the women have found success despite their different songwriting styles--in this case combining elements of country, punk and pop with their harmony-driven folk-rock. A couple of songs from the record are streaming at the Girls' MySpace page and their latest video, "Rock and Roll Heaven's Gate," is streaming at their website.

The Indigo Girls have also launched their own YouTube channel, where fans can check out all their latest videos.