The most Americans in recent years are heading to national parks in recognition of the U.S. National Park Service’s 100th anniversary on Aug. 25. Visitation to the national parks reached an all-time high in 2015, with more than 307 million visitors, according to the National Park Service, and travelers can expect the parks to remain busy in the year ahead. According to a recent AAA survey, 79 percent of Americans say they are as likely (42 percent) or more likely (37 percent) to visit a national park in the next 12 months, building on the momentum of this year’s centennial celebrations.

“The demand for national parks is off the charts this year, and it’s exciting to see that Americans are poised to take even more national park vacations in the years to come,” said Gail Weinholzer, director of public affairs, AAA – The Auto Club Group. “In times of global uncertainty, many people are turning to domestic vacations and the wide variety of national parks offer something for every traveler to discover.”

Eighty-five percent of Americans have visited at least one national park, and a majority says the national parks are a “must-see” vacation destination (73 percent). National parks are growing in popularity among younger generations, with nearly half of Millennials (46 percent) citing that they are more likely to visit a national park in the next year, outpacing both Generation X and Baby Boomers.

“It’s not surprising to see that younger generations are particularly interested in visiting national parks,” added Weinholzer. “Travel is part of Millennials’ DNA, and they consistently seek experiential travel opportunities, a major draw for national park visitors.”

According to the National Park Service, the most visited national parks in 2015 were Great Smoky Mountains, Grand Canyon and Rocky Mountain. AAA’s survey revealed the national parks that top most Americans’ bucket lists for future travels include Yellowstone (33 percent), Yosemite (17 percent) and Grand Canyon (12 percent).

Americans feel the best times to visit the national parks are during the spring (35 percent), fall (33 percent) and summer (27 percent). Travelers planning trips to national parks for the remainder of 2016 can enjoy a discount on select dates in honor of the National Park Service’s 100th anniversary. All sites that charge an entrance fee will offer free admission Aug. 25-28, Sept. 24 and Nov. 11.