3 major national parks remove timed-entry requirements. See which ones.

Three of America’s most popular national parks will be easier to visit this summer.

In a break from recent years, Arches, Glacier and Yosemite National Parks are lifting the timed-entry and reservation requirements they've had in place for their peak visitation periods, the Department of Interior announced Feb. 18. Advance reservations aren't required for Yosemite's current firefall season, either.

“We’re expanding access where conditions allow and using targeted tools only where necessary to protect visitor safety, maintain emergency access and preserve these extraordinary places for future generations,” Acting Assistant Secretary for Fish, Wildlife and Parks Kevin Lilly said in a news release.

Other types of temporary traffic management measures may be enacted if parking areas or roadways reach capacity in the parks, the Interior Department noted, adding that Glacier would actively monitor busy corridors like Going-to-the-Sun Road. 

"Parks use a combination of seasonal staffing increases, traffic control measures, real-time visitor messaging, expanded transit operations and interagency coordination to manage crowds safely and responsibly," an Interior Department spokesperson told USA TODAY. "Lifting timed entry does not mean lifting management. It means parks are using the full range of tools available to balance access, safety and resource protection."

Concerns about crowds

Conservation groups like the Coalition to Protect America’s National Parks and the National Parks Conservation Association have expressed concern that lifting reservation requirements will lead to overcrowding and possible harm to park resources.

SFGate reported "parking lots filled completely, traffic jams gridlocked the park, shuttles were delayed for hours, and parkgoers stuck outside in the cold" at Yosemite over Presidents Day weekend, as visitors flooded the park in hopes of seeing firefall. Between February and March, when the setting sunlight hits just right, it looks like a ribbon of fire flowing down El Capitan. The annual phenomenon always draws huge crowds, but previously required reservations.

"Yosemite prepares for high-visitation events like Firefall months in advance. Shuttle capacity, traffic flow, law enforcement presence, emergency response posture and visitor communications are all part of a coordinated operational plan," the Interior Department told USA TODAY. "When visitation spikes during a short, weather-dependent natural phenomenon, there can be temporary delays. That is not evidence of mismanagement. It is the reality of hosting one of the most popular natural events in the country."

National parks with reservation requirements 

Travelers should note that the National Park Service isn't eliminating timed-entry entirely. Timed-entry and other types of reservations are still required at other national parks. 

• Acadia National Park will require timed-entry reservations for vehicle access to Cadillac Summit Road from May 20 through Oct. 25. 

• Haleakalā National Park requires year-round reservations for viewing sunrise from its summit.  

• Rocky Mountain National Park will require timed-entry reservations May 22 through mid-October.  

• Shenandoah National Park requires day-use tickets to hike Old Rag Mountain from March 1 through Nov. 30. 

• Zion National Park requires permits to hike Angels Landing year-round. 

(This story has been updated with new information.)