I'm a liberal but I still have to point out that "the country's depopulated and backwards interior" (your own words) provides the food, agricultural products, and mineral plus other natural resources that cities depend on. Until urban areas manage to figure out how to conjure their food and industrial input out of thin air, rural areas are as important (and arguably more important) than cities.

It's also worth noting that a large portion of the armed forces come from rural areas. Need I point out the potential problem with a military that doesn't hold the same values as the civilian populace it's supposed to protect and obey? Bear in mind that history does have a nasty habit of repeating itself.

The number of people living along the U.S. coast is currently 123 million (https://www.natureworldnews.com/articles/1022/20130326/popul...). With a population of more than 327 million people (https://en.wikipedia.org/wiki/United_States), the coast is a bit more than 1/3 but significant less than half and quite far from being majority.

(This is not a comment about calling it urban pockets. 123 millions is a lot. Just a note in regard to the statement that it could be called the majority.)