There are about 275 cities in the US with populations 100,000 or larger (Wikipedia link). 201 of these cities are small, with populations between 100,000 and 250,000. There are 30.3 million people living in these cities -- about 10% of the US population. A certain number of these cities fall within the metropolitan areas of larger cities, but a significant number are at least 50 miles from a major city.
Here is a map of 200 cities with populations between 100,000 and 250,000:
View Small Cities in a larger map
And here is a map of 25 cities with population greater than 500,000 (red) and 48 cities with population between 250,000 and 500,000 (green):
View Small Cities in a larger map
Google Maps limits the number of objects that can be placed on a map to 200 items, so it isn't possible to overlay these maps using Google Maps. Google Earth does not have this limitation, and all these points are included on the Google Earth version of the map. Here is what the overlay looks like:
And here is a map of the Metropolitan Statistical Areas in the US in 1999. Wikipedia provides an up-to-date list of the MSAs in the US (link). (Many of the small cities actually constitute an MSA of their own; so determining whether a small city is "metropolitan" really involves the question of whether the place falls within one of the top 25-50 MSAs by population.)
The group of cities I'm interested in here is a subset of the cities on the first map: those that are more than 50 miles from one of the top 25 cities on the second map. This still leaves well over 100 cities in the United States with a couple of interesting characteristics: they are relatively small, so they can be expected to lack a number of higher-level functions and industries; and they are relatively isolated from other larger cities, so their populations are extensively dependent on the resources of the city itself for employment, social services, entertainment, consumption, education, etc.
So the takeaway question here is this: what is life like in Billings MT, Topeka KS, Norman OK, Pueblo CO, Springfield IL, Knoxville TN, Cary NC, Green Bay WI, Grand Rapids MI, Allentown PA, Shreveport LA, and Killeen TX? What is it like to grow up in these places? Where do young people go for post-secondary education? What percentage of young people leave these places permanently in the course of their careers? Where do the elected officials in these places come from? How are these cities doing, from the perspective of unemployment, neighborhood and business district decline, and social problems?
Further, we can ask whether there are any structural features in common that imply that these places are more similar to each other than they are to larger cities or smaller towns. Are issues of immigration, race relations, drug use, teen pregnancy, or high school dropout rates different in these places?
Finally, we can ask whether growing up in these places gives rise to a specific mentality. Do those of us who grew up in small cities like these -- Peoria, Rock Island, Springfield -- have a different set of values, a different way of looking at the world, or perhaps different ways of relating to people in ordinary social life? Or are regional differences (south, midwest, Pacific Coast) more of a determinant of one's mentality?
(I've placed the lists of cities and MSAs I've used here as spreadsheets at Google Docs; link, link. Both lists come from Wikipedia entries on US Cities and Metropolitan Statistical Areas.)