Twenty Year Blues marks the 20th anniversary of the Nashville Bluegrass Band, and they're still at the top of their game. The sound is pure bluegrass, but they aren't afraid to stray from tradition, and remain one of the only bluegrass bands to incorporate songs from the black string band tradition as well as black gospel music. Traditional tunes and Bill Monroe tunes sit very nicely with their covers of "Travelin' Railroad Man Blues" and "Sitting On Top of the World," both old string band songs, originally performed by the Alabama Sheiks and the Mississippi Sheiks, respectively, in the '30s. They also do a fine vocal gospel version of "Hush (Somebody's Callin' My Name)," which goes back to the '20s in a recording by the Wiseman Sextette. Then they turn around and cover "Luckiest Man Alive," which talks about the Vietnam War (not common bluegrass subject matter). They know the tradition, and understand how to expand it without ruffling any purist feathers. The playing is stellar, as would be expected from these longtime session men, and their close harmony singing is wonderful. Here's to another 20 years.