National parks may get all the attention, but state parks pack in visitors, especially during fall, when cooler weather invites exploration, says Richard Dubi, CEO of ParksByNature Network. The company publishes the free Pocket Ranger guides, the official app offered by several dozen state recreation and wildlife departments. "People are passionate about their state parks. There are a lot of hidden gems there." He shares some favorite parks for fall fun with Larry Bleiberg for USA TODAY.