Over the last couple of years, Boston roots-folk act The David Wax Museum has been a mainstay at group houses across Northwest. These house concerts afforded lodging and modest merch sales for Wax and Suz Slezak, his fiddle- and jawbone-playing compatriot. The parties, here and elsewhere, also consolidated a growing fan base that would elect the band, via online ballot, to the Newport Folk Festival’s  listener’s choice slot at the 2010 festival. This year, Wax and Slezak were invited again to the annual Newport, R.I., concert, not as a wildcard but as an established act. They opened yesterday at Newport’s mainstage, a distinct upgrade from the Quad stage where they had debuted the year before.

The Museum played before acts like Carolina Chocolate Drops (gospel hoe-downs, approximately), Wanda Jackson, and Amos Lee, and a day after Gillian Welch, Earl Scruggs, and the Decemberists, whose presence explains why Newport sold out this weekend for the first time in its 52-year history. Wax’s band, including a smart three-piece horn section and a Mexican son jarocho dancer, displayed its usual panache, and made a strong argument for why the festival should still exist.

Newport has something of a dual personality these days, exemplified in the divide between the “dancing section” (yes, there is actually a dancing section) and the lawn-chair section. Concomitantly, we had the nostalgia acts and the Bob Boilen-approved youngbloods; this is an oversimplification, but not as drastic a one as you might think. Heavyweights such as the Decemberists are called in to round out the crowd, but meanwhile the relevance of the proceedings (if we still worry about these things) is, I think, a healthy question.

Folk music as a rule toes the line between calling out the bullshit pieties and preserving the needful ones. Most traces of purism are gone from Newport. After a heavily distorted “Legionnaire’s Lament,” Colin Meloy could safely joke: “Pete did not brandish an axe for that one.” (Seeger was not only present but within axe-swinging distance; for a gloss of Meloy’s reference, see here.) That’s a good thing: Mavis Staples kills when she has an electric band behind her, and Wanda Jackson offers a warm and witty rockabilly set—though Newport’s Gospel deficit remains troubling. Still, we’re talking about a festival that came of age fighting the Man (see: “This machine kills fascists“); it’s hard to maintain that attitude when you’re suddenly onstage at the pleasure of the Man’s Prius-driving brother.

The best answer I think is when a festival—however hoary, however sponsored—makes possible the national debut of otherwise marginal or regional acts. On my ballot, this year’s emergent big-timers included several fantastic female harmony groups such as The Secret Sisters and Mountain Man, a trio that combines three-part barbershop with more intricate, canticle-like arrangements to glorious effect. It would be delightful to see both groups return next year. David Wax has proven that success at the festival does not go unrewarded, though residents of Mount Pleasant may well mourn to find that he isn’t knocking on their doors as often as he used to.

Photograph of David Wax at Newport by Annie Galvin