The thing I've noticed about the Dollar General expansion is they're building stores in rural communities some distance from the county seat, even larger towns that may have a Walmart or Kroger. Or they are building near traffic generators, such as large employers. It's something like the convenience store concept, except the prices are cheaper, and not artificially high like you'll find for a bag of chips at a Sheetz or Speedway.
Examples: DG recently opened a store in Wolfe County, near a factory. Granted, it's in a crossroads community that's 12 miles from either Campton or West Liberty, and 20 miles from Salyersville and Jackson, but the prime customer base is people leaving work and needing to stop and get something on the way home. They also opened one a few years ago at the entrance to an industrial park in northern Perry County.
And although most county seats have both a DG and a FD, and some have two of each, DG has been more aggressively expanding. In fact, DG built and opened a new store in my town last year, only about three miles from their existing location.