I am not sure exactly why but take a look at the U17 men's national team, I only see 1 from Baltimore area and 1 from the DC area. 20 years ago, you would see 5 or 6 players from this area on each team. The u15 and U16 has 1 player each. You are starting to see more and more players come from the warmer areas of the country because they can easily play year round. Florida is a good example. Florida has also started soccer academies in which kids can pay a fee, to attend the academy, get 4 hours of soccer instruction a day and then do virtual schooling. Its similar to the IMG football high schools but they start much younger.