Soul Train, the longest-running weekly syndicated program in television, gave black artists and dancers a forum when there was no interest from the major networks. This fine three-disc boxed set celebrates the show's two decades and serves as a good overview of how contemporary black pop has changed during its run. The opening disc is by far the most diverse; during the mid-'70s, there was still room for Southern soul and blues, stylish pop, funk, and vocal groups. The second disc mirrors the turn toward more sophisticated production, a less soulful sound, and the coming of disco. The final CD begins with light soul and pop-tinged fare, then slides into rap, hip-hop, and new jack swing. Most of these songs are available elsewhere, but this collection gives listeners a consistently entertaining tour. Rhino deserves bonus points for using all original versions throughout.