National parks refine ticketed-entry systems to manage visitor boom Rocky Mountain National Park in Colorado requires timed entry By: Laura Olson - July 29, 2021 5:15 am Park visitors walk up the dunes at Great Sand Dunes National Park and Preserve in Colorado in February 2017. In the distance the snow-capped Sangre de Cristo Mountains rise above the dunes. (Mackenzie Reed/NPS/Public domain) WASHINGTON — Watching the sunrise from Cadillac Mountain at Maine’s Acadia National Park is a gorgeous view — so breathtaking that on some days, as many as 500 cars could be found vying for the scenic overlook’s 150 parking spots. That competition has become more manageable since Acadia officials began using a reservation system in May, according to the park’s superintendent, Kevin Schneider, who testified to federal lawmakers Wednesday about overcrowding in national parks.