Steve, no offence meant, but it would appear that you have not the right perspective on population density.
I sure believe that there are overpopulated areas in urban Michigan, but there are underpopulated areas in Montna, in the MOjave desert and in many other places.
Besides, it is not our impressions, but the number that speak. Inthe following Wikipedia link there is a list of countries and dependencies by population density.
https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_population_densityAbsolute 1st is Macau, with a whopping 21000 people per square km
Italy, which is pretty much populated, but not evenly (urban areas include most of population) is 75th with 195 people/km2
The USA are 186, among the less populated nations, with a measley 35 people/km2, which is 18% of the population density of Italy.
Saudi Arabia, which is a huge desert, contains half the population density of America. America has twice the population density of a huge desert, so ist population appears to be very sparse on average.
So, America cannot really be defined overpopulated, on the contrary, it appears to be underpopulated hence Mr. Trump with Mr. Vance are providing sound suggestions to try and support more numerous families.
I agree with your reasoning if it refers to overpopulated areas in some parts of America. The crowds in there should be redirected toward desertic areas, with huge development projects. But that's another issue.