GREENVILLE — Conservationists are still working to finish South Carolina’s mountains-to-sea Palmetto Trail nearly 20 years after it was designed.

The trail was planned to be about 425 miles when first drawn out in 1994. If it ever gets finished, it will likely be almost 500 miles, winding through cities, historic towns, through marshes and atop mountains and maybe even over the Jocassee Dam, said Natalie Britt, executive director of Palmetto Conservation Foundation, which is organizing the trail.

“It connects some of the most important public lands that we have. No initiative in the state tells the story of South Carolina better than the Palmetto Trail,” Britt told The Greenville News.

Hopes to finish the trail were boosted this year when Boeing donated $100,000 to the foundation to draw up a new master plan for routes that would finish the trail.

Most of the incomplete sections are in the Upstate, hampered by mountainous terrain and a patchwork of private and public land, Britt said.

The trail starts at the sea with the seven-mile Awendaw Passage along boardwalks in the Buck Hall National Recreation Area. It winds its way north 162 miles all the way to Wateree in the Midlands, where the gaps begin, Britt said.

Some ambitious projects on the trail are already completed. From Peak to Prosperity in the Midlands, volunteers rebuilt decking and an abandoned railroad bridge in a three-quarter-mile span across the Broad River.

Britt hopes some of that ambition crosses over to the gaps in the Upstate. One of the key incomplete sections is through the Jocassee Gorges. A section in Pickens and Oconee counties would go through property owned or managed by the state Department of Natural Resources, the state parks service, the U.S. Forest Service, a private landowner, a private foundation and Duke Energy. All of them will have to agree to a route.

“DNR is working with the Palmetto Trail to work out a route in the Jocassee Gorges that creates a wonderful hiking experience and meets the objectives of both organizations,” DNR spokesman Greg Lucas said.

Britt hopes the entire trail will be finished in five to 10 years.

“I really think we’re starting to identify how to close those gaps,” she said.