WIND CAVE NATIONAL PARK, S.D. (AP) — Wind Cave National Park says it set a modern-day visitation record in 2015.

Park officials say visitation at the world's sixth-longest cave was up 9.8 percent to about 109,000 people. It's the highest since 1971, before tours were limited to 40 people.

More than 70 percent of the visitation occurred between June 1 and Sept. 1. The busiest days were Tuesdays and Wednesdays and days with rain.

More than 138,000 people visited the cave in 1968. Because of the park limiting tour sizes and rerouting Highway 385 to bypass the park visitor center, park staff believe the historic 1968 figure will never be exceeded.

Park Superintendent Vidal Dávila says the National Park Service is celebrating its centennial this year, and the park is looking at possibly breaking the record again.

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