The Indigo Girls have always had a hauntingly impressive grasp on gorgeous polyphonic harmonizing. They focus sharply on shaping their vocal arcs, making sure to play out the harmonies in a way that best serves the songs’ thoughtful lyrics. And though they have been performing together for over a quarter century, both Amy Ray and Emily Saliers have politely declined the opportunity to mellow with age.

Devoted environmental and social justice activists and lifelong music-industry mavericks, Amy and Emily have spent their entire careers pushing boundaries on a variety of fronts, but when you boil it down, the secret to their success lies in the fact that the Indigo Girls flat-out write wonderful songs.

Show Time: 7:00pm, Gates: 6:00pm