WINHALL, Vt. – Nearly 25 years after three friends laid the groundwork for it by skiing the length of Vermont, the 300-mile Catamount Trail – a backcountry ski trail extending from Massachusetts to Canada – is complete.

Volunteers cleared and marked the final 4 1/2-mile leg running through the Green Mountain National Forest in southern Vermont last month.

“It’s quite an accomplishment,” said Jim Fredericks, executive director of the Catamount Trail Association. It took “a lot of very hard work by a lot of people to make it happen.”

But he acknowledged that there’s a lot of work to do before the entire trail, which is supported by members of the nonprofit Catamount Trail Association, is secure.

Getting easements for the roughly 150 miles of trail that cross private land and moving the trail off snowmobile routes for the safety of skiers are two big challenges.

“It’s the private property we have the most problems with… If someone sells it, we don’t have any easement,” Fredericks said.

Although 80 miles of the trial runs through the Green Mountain National Forest, the latest section was held up until an updated management plan for the forest was adopted this year.

The trail, which starts on the Massachusetts border in Readsboro, runs through the Green Mountains traversing a variety of terrain, from the groomed trails of cross country ski centers to remote mountain passes, such as the famous section from Bolton to Trapp Family Lodge in Stowe. There are also gentle sloping trails through fields and forest land and inn-to-inn skiing in some spots. Snowshoers also are welcome.

But the route has changed over the years from the path Steve Bushey, Paul Jarris and Ben Rose embarked on in 1984 as part of Bushey’s University of Vermont geography project.

A fourth friend, Andrew Painter, helped with transportation and logistics.

“We skied for three weeks and we ended up in Canada,” said Rose, 47, now director of the Green Mountain Club.

Along the way locals familiar with the back country helped, some joining the group for a ski.

“It quickly became the effort of a lot of people,” Rose said.

The Catamount Trail Association was formed the same year to develop and maintain the trail and now has 1,800 members.

After seeing an ad in Backpacker magazine in the early ’80s, John Stearns of Bridgewater joined as a charter member. Now 73, and a member of the board, he helped scout and clear the last leg in Winhall.

“It’s been quite an effort and quite a challenge,” he said of the trail’s completion.

Stearns also is among the estimated 60 people who have skied the entire trail, which the association says is the longest ski trail in North America.

Members pay $35 a year to support the trail and in return get half-priced tickets to 23 cross country ski centers and eight downhill resorts. The association also provides guidebooks, maps and a web site.