Welcome to Flyertalk.

In a perfect world in which your flight is on time or early, you are among the first to deplane, your bags are among the first on the carousel, and there is no line at security, you should have no problem.

Otherwise, you should have a backup plan. LGA in the summer...planes can be delayed because of thunderstorms in NYC or from elsewhere. The carousel could be slow with your bags coming out toward the end. Then there is security. The lines could be slow and long.

I think you'll need to be lucky to make that second US Air flight. At least you won't have to go from terminal to terminal.

If you really need to make that flight, don't check in any bags. Then you won't have to leave the secured area. That's the huge problem outside of your original plane arriving very late. Going back through security could be awful. So why do it? This you can control. Keep your bags with you. Pack efficiently so you don't have to check in anything.