whistle stop

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A town or station at which a train stops only if signaled.
• noun A brief appearance of a political candidate in a small town, traditionally on the observation platform of a train.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a small railway station between the principal stations or a station where the train stops only on a signal