Reid had been with ESPN since 1982 and is the only television play-by-play announcer to cover five different North American motorsports series. He's called NASCAR's Sprint Cup, Nationwide and Truck Series, as well as IndyCar and NHRA.
An ESPN spokesman says the network is going in a different direction and Allen Bestwick will call the remainder of the Nationwide Series races this season.
Reid was the network's lead announcer for IndyCar and that position will be addressed later.
Reid erred during the Sept. 21 Nationwide Series race at Kentucky when he called the win for Ryan Blaney one lap shy of the finish. Bestwick called Saturday's race at Dover instead of Reid.