An excellent question. You figure California and Texas have a lot of instate competition, but it really does make USC and Texas look like rather huge underachievers historically. USC is #1 in nfl players btw. Cal is #9 (kill me now).
why? players want their parents to be able to drive and see them play. every study ever done on recruiting shows location is by far the #1 factor. If you'd like a different distance, propose it and back it up.
sounds like a richt problem to me. teams raid California as well, but under kiffin and carroll only a handful of elite southern California recruits went elsewhere.
the collapse is texas recruiting in favor of A&M is something I never thought I'd see. what percentage of the state grew up as texas fans? 70%? 80%? there is a reason why they literally used to pick and chose who they wanted in state. I imagine A&M will continue to pull top talent, but it's hard to believe they will do better than texas long term if texas' coach has a pulse.
You said within 20 miles. Mississippi and Louisiana are pretty much the same size in terms of total land area (ranking 31 and 33 in the US, respectively). Louisiana is much more densely populated, so more likely more talent within a shorter distance.
USC has some issues too. mostly that they limit their hires to the "Trojan family." Unlike Texas, historically, though USC will pay big money to stay competitive.