Yehuda Gilad at University of South California ((http://www.usc.edu/schools/music/private/faculty/gilad.php)
happens to be one of the best (if not, *the* best) clarinet teachers in the U.S. for undergrad students; however, I've heard that if you want to major in clarinet performance, you are required to for a double major. His students probably get the majority of the clarinet orchestral jobs that are out there. The auditions at USC; however, are extremely competitive - I think he only takes two to three people per year.
I've also heard good things about Yale University and University of Michigan - Ann Arbor.
I was considering going to University of Minnesota - Twin Cities for clarinet performance, but the clarinet teacher there, Burt Hara, will be leaving in the next year. Instead, I am attending University of Wisconsin - Eau Claire by recommendation and because everyone there is an undergrad, in contrast to U of M which has master's and doctorate programs. What that means that I have more opportunities to perform in UW-Eau Claire.
Don't forget about Curtis, Julliard, DePaul University, etc. You still have time - do all you can to prepare yourself before you do head out to college and you don't have time.
Clarinet jobs are scarce - make sure you have a backup plan (I'm double majoring in Clarinet Performance and Mathematics). To demonstrate this fact, there's a Facebook group titled "Clarinet Jobs." There aren't too many.