Idioms and Phrases with one-horse town
A small and unimportant place, as in Ours was just a one-horse town until the nuclear plant was built. This expression, first recorded in 1857, presumably alluded to a town so small that a single horse would suffice for its transportation needs.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.