While National Parks have always had a very dedicated fan base, the number of visitors has soared to new heights after the pandemic and generally stayed steady even as international travel also became possible. Many set the goal of visiting all 63 despite the fact that some are so remote that getting there would require special gear and thousands of dollars in flights and accommodations.

Amid the high traffic, different parks have been trying different ways to navigate the high numbers of visitors. Some have been raising fees while more and more are resorting to an entry system in which one has to book one’s visit ahead of time.

Related: I visited two of the country’s most underrated National Parks — here’s what it was like

In March, Mount Rainier National Park in Washington State announced that it would start requiring those entering through its Paradise Corridor from the Southeast and Sunrise Corridor from the northeast during the summer season to register the two-hour slot in which they plan to come online.

Want to visit this National Park? You’ll have to register

Spread across Colorado and loved for spotting mountain wildlife such as elk and moose, Rocky Mountain National Park first introduced the slotted entry system for the summer of 2023. Prior to arriving, one had to go online and pick the two-hour slot in which one planned to enter. While this can be done at the last minute if space is available, it is a way for the park to shut off entry if it gets too busy.

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Rocky Mountain just announced that the same system will be in place for the period between May 24 and Oct. 20 from 5 a.m. to 6 p.m. To avoid people booking up all the tickets ahead of time and then reselling them, Rocky Mountain will also release 40% of the passes at 7 p.m. of the night before each day starting from May 23.

Reservations can be booked online on Recreation.gov and open on the first of each month for two months ahead — on June 1, one will be able to book slots from that date until July 31. Those trying to access the park’s Bear Lake Road that is especially known for hikes and scenic views will also need to book an additional Timed Entry + Bear Lake Access pass.

Related: A beloved national park is about to get a whole lot more expensive

There is a reason the National Park Service has to do this

In addition to the entry fee of $30 per vehicle (those getting dropped off pay $15), one will have to pay a $2 processing fee to book the reservation online.

While all this may sound complicated to those who were used to just driving up to the park when the desire hits, the National Park Service says it is a way to mitigate overcrowding that has started to take a toll on both staff and visitors.

“Rocky Mountain National Park is one of the busiest national parks,” the NPS explains on its website. “Visitor crowding and congestion at RMNP have led to increased negative impacts to visitor and staff safety, resource protection, visitor experience and operational capacity. The park has piloted various visitor use management strategies, including managing vehicle access in highly congested areas on a first-come, first served basis (that) had some limited success initially, but over time began to lose effectiveness.”