BAR HARBOR, Maine (AP)   Maine’s only national park is working on options to accommodate a surge in visitors that has made parking difficult.

Acadia National Park is one of the most popular destinations in Maine in the summer. The number of yearly visitors ranged between 2 million and 2.5 million from 2000 to 2013, but has surged since. The Portland Press Herald reports there were 3.5 million visitors last year.

The park had its busiest day in its history this July 5 with 35,000 visitors. More than 600 cars attempted to access 157 parking spots on Cadillac Mountain at sunset that day.

Plans to expand three parking areas are expected to help ease the burden. There are also plans for expanded bus service and a parking reservation system at some particularly popular areas.