Thirty-five dollars for a ranger-led tour, four-hour minimum, in Big Bend National Park in Texas.    Three dollars for a living history tour at Bent's Old Fort National Historic Site in Colorado.

    Just as promised earlier this year, a coalition of conservation groups has filed a lawsuit in a bid to stop the federal government from removing grizzly bears from Endangered Species Act protection.

    Debate over what drives, or doesn't drive, national park visitation has been going on for years. In recent years, though, it's grown particularly alarmist, as if the parks were becoming passe, no longer the darlings of America's vacationers, in danger of withering on the vine because they weren't been overwhelmed by tourists every day of the year.