I am also in St. Louis and having the same issue with my iPhone 5.  Funny thing is, when I first got it, it would switch to 4G and I would still be able to browse.  I took it to the Apple Store and the Genius there told me he has the same issue and he was told by AT&T they are aware of the issue and addressing it.  Not sure if that was just to pass the buck to someone else or not, but I registered just to let people in this thread know, especially since I saw so many people in this thread from St. Louis.  Also, I live near The Hill area and I am having this issue no matter where I am in St. Louis.