Rocky Mountain National Park Aspenglen Campground

July is the peak demand month — 20.0% of its 6,079 reservations are secured 6+ months in advance, making it the hardest month to book park-wide. August offers a slight edge for last-minute campers at 33.2% of bookings made within a week, while September brings fall foliage, elk rut, and 31.1% last-minute availability with meaningfully lighter crowds. May is the most accessible entry point of the season, with 31.5% last-minute bookings and the lowest share of far-out planners (8.9%).

A timed entry permit is required to drive into Rocky Mountain National Park during peak season (typically late May through mid-October), and permits must be secured before arriving at the entrance gate — not at the gate itself. The Bear Lake Road corridor, which serves Glacier Basin Campground, is the most congested road in the park; the park's free shuttle system connects campgrounds to trailheads along this corridor and is the preferred way to access Bear Lake area trails once you're camped. Timber Creek Campground on the west side is not connected to the east-side shuttle system and requires driving Trail Ridge Road to access the park's east side.