A run selection mechanism is provided for selectively directing the flow of particulate material from an air cart. The mechanism includes a chute for receiving metered particulate material. The chute has an output. A first primary conduit has an output communicating with a first pneumatic primary run and a second primary conduit has an output communicating with a second pneumatic primary run. A selector selectively directs the metered particulate material to one of the output of the chute, the first pneumatic primary run and the second pneumatic primary run.