Indigo Girls are among the most enduring musical outfits to emerge from the late-’80s female singer/songwriter scene and to a lesser degree the later iteration of the Athens, Georgia scene that birthed R.E.M., Love Tractor, and Widespread Panic. The Grammy-winning duo of Amy Ray and Emily Saliers established a devoted national fan base thanks to early hits such as ‘Closer to Fine’ from their self-titled Epic release in 1988; it was the first of six consecutive gold- and/or platinum-certified albums. Their two-women-with-guitars formula may not have been revolutionary on paper, but the combination of two distinct musical personalities and songwriting styles provided tension and an interesting balance. Saliers, hailing from the Joni Mitchell school, boasted a gentler sound but was more compositionally complex, with lyrics that revealed the abstract and spiritual. Ray drew heavily from the singer/songwriter tenets of punk rock, citing influences such as the Jam, the Pretenders, and Hüsker Dü for her more direct, often confessional approach. Indigo Girls are celebrated almost as much for their political and social activism on such issues as LGBTQ and Native American rights, protecting the environment, and work against the death penalty. With a passionate live show that consciously sought to erase distances between audience and performer, they grew a fan base across U.S. borders into Canada and Europe. Later recordings, such as 1994’s Swamp Ophelia, led by the charting single ‘Least Complicated,’ sustained their appeal even as their sound expanded to include Americana, rock, and even blues. To bring across their vision, they employed touring bands filled with top-shelf musicians including Budgie, Sara Lee, Gail Ann Dorsey, Brady Blade, Matt Chamberlain, Jane Scarpantoni, and Caroline LaVelle. After leaving Epic, the Indigo Girls delivered Grammy-nominated Top 50 albums for the Hollywood, Vanguard, and IG labels, including 2006’s Mitchell Froom-produced Despite Our Differences, 2009’s Poseidon and the Bitter Bug, and 2011’s Beauty Queen Sister. Their 15th…