FLAGSTAFF, Ariz. (AP) — Many of the country's most prominent national parks, including Grand Canyon, Yellowstone and Zion, set new visitation records in 2015.

Officials say the records could be short-lived as the National Park Service celebrates its centennial in 2016, when even bigger crowds are expected. The agency has been urging Americans to rediscover the scenic wonders.

Overall visitation is on track to hit 300 million for 2015, besting last year's all-time high of nearly 293 million.

Absent December totals, Grand Canyon in northern Arizona has almost 5.3 million visits. Zion in Utah has 3.5 million. Yellowstone, which stretches into Montana, Wyoming and Idaho, is nearing 4.1 million.

Yosemite in California is about 220,000 visits shy of the 1996 record_4.2 million — with November and December still left to count.

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