5G In The USA Will Go To Where The Money Is First.

When FCC approved Sprint - T-Mobile merger, one big argument to promote the deal of 5G deployment bringing high-speed broadband service to rural populations in the US. The FCC and others proclaim that 5G will bring broadband to the masses outside metropolitan areas. Ajit Pai can try as he may to make this look sweet but it is not going to happen without substantial government subsidies. The truth is that rural areas are at the bottom of the list of priorities for every major communications carrier. 
It no wonder that the money is in the areas with densest populations, the dark-blue areas in this US sensus map will be served first. Early 5G trials are going on these places. The light-green areas will wait something like 10 years or more. The rest is in between
The technology is new and the carriers will spend tens of billions per year building out 5G infrastructure. Naturally, they will prioritize locations that will yield the best returns. Revenue per square mile is the metric to watch. My $50 per month for 5G and 10% penetration rates are very low to make a point that even if it's cheap, there is big money in dense areas.
This should give you some indication;

ZDNET