By Brady McCombs, The Associated Press SALT LAKE CITY — Visits to U.S. national parks set a record in 2016 for the third consecutive year as landmarks such Zion, Yellowstone and Rocky Mountain experienced historic levels of popularity that brought collateral headaches stemming from overcrowded roads and trails and increasing visitor misbehavior. At many parks, visitors waited an hour or more in cars to get through entrance gates and then spent the day trying to outmaneuver fellow visitors for parking spots and room on popular trails.