In celebration of its 20th anniversary, Rounder Records, arguably the country’s premier roots-music record company, has sent three of its heavyweight acts—Marcia Ball (pictured), Steve Riley, and Beau Jocque—on tour together. The hardworking triumvirate and their bands should keep the Alley’s small dance floor busy all night with a cornucopia of Louisiana rhythms: Ball’s sultry rockin’ New Orleans R&B, Riley’s vibrant, upbeat Cajun stylings, and Jocque’s sweat-inducing, bottom-heavy zydeco. At 8 p.m. at Tornado Alley, 11319 Elkin St., Wheaton. $22. (301) 929-0795. (Steve Kiviat)