I have no idea where Melissa lives, but perhaps there's a large military base in some other part of her county. While the survey asks for zip code, it seems to categorize areas by county, with no regard smaller areas within the county, not even individual zipcodes.

With a town population under 450 people, and a total county population around 8500, it sounds like a fairly sparsely populated area that may well contain a lot of farmland and/or forest between communities. That describes a fairly typical setting for, say, an Army or Marine training base, which requires a lot of wide-open space. I wouldn't be surprised to learn that such a base might be located at the other end of Melissa's county, so far away from her little town as to have no local impact there at all.