During the California gold rush era, a mining town now called Placerville was known as Hangtown because of the number of hangings imposed for crimes. Nashville-based singer and former Washington Post writer Eric Brace was born in Placerville and once wrote a Post travel piece about the region. Brace was also fascinated by the folk standard “Sweet Betsy From Pike,” which tells of the tribulations of a pioneering couple who travel by stagecoach to Hangtown. The sing-along ends at a dance when Betsy’s man Ike falls into a jealous rage and demands a divorce. Brace has added songs and turned the couple’s tale into a folk opera called Hangtown Dancehall. Written with D.C. musician Karl Straub, who also sings on some tracks, this is a decade-in-the-works effort. There are lots of narrative-heavy cuts with acoustic strumming, but also dashes of tango and strings-aided Nashville-style countrypolitan. The star of the D.C. premiere, though, may be another former local, Kelly Willis, playing Betsy. Her smoldering drawl enlivens every cut she’s on. Oct. 3 at the Birchmere. $29.50.