Yellowstone National Park recorded its slowest year since 2014 last year, with visitation numbers dropping by a little more than 2% from 2018’s total.

Park visitation stats released Wednesday showed the park had 4.02 million visits in 2019, a dip from the previous four years, which either neared or topped 4.1 million visits.

Linda Veress, a park spokeswoman, said they don’t have an explanation for the drop but that winter weather arriving in the fall may have played a role. She also said it follows a trend since 2016, the park’s busiest year on record with more than 4.2 million visits.

“It has been steadily decreasing since 2016,” Veress said.

Despite the drop, though, the park remains busy. It’s the fifth consecutive year that total visits exceeded 4 million, a total the park didn’t reach for the first time until 2015. The highest total before 2015 was just 3.6 million.

The number of visits doesn’t correspond directly to the number of people passing through the park’s gates. It’s based on the number of cars that come through the gates multiplied by an estimate of people-per-vehicle.

The drop from 2018 amounted to almost 100,000 visits. It was about 77,000 fewer visits than 2015.

Traffic ebbs and flows throughout the year, with summer being the busiest time. The busiest month of the year was once again July, with more than 936,00 visits recorded. The slowest month was November, with about 15,600 visits.

A report on the National Park Service’s statistics site shows there were weather-related road closures in September and October.

Snow in late September shuttered North Entrance and East Entrance roads temporarily, the report says. Additional weather-related closures over about 10 days in early October also reduced visitor numbers, according to the report.

Winter season is now in full effect in Yellowstone, with snowmobile and snowcoach tours running through the park. Only the road from Mammoth Hot Springs to Cooke City stays open year-round. All others are restricted to snowmobile and snowcoach traffic.

Winter traffic ends on those roads in March and roads will open to vehicles again beginning in April.