WARMER, SAFER, DRIER: That is the motto for these volunteers from Princeton United Methodist Church who recently spent a week working to improve houses and trailers in Appalachia. The church has been sending volunteers to the region for four decades as part of the national Appalachian Service Project.

Each summer, 14,000 volunteers from across the country travel to Appalachia to help improve living conditions for those less fortunate. Two local churches, Princeton United Methodist and Nassau Presbyterian, have sent groups this month. Their goal, and the slogan of the Appalachian Service Project (ASP), is to make trailers and other dwellings in the mountain region “warmer, safer, and drier.”

Sixteen teenagers and seven adult volunteers made up the PUMC group.

“Some of our people took out carpeting and fixed flooring and supports and laid down some laminate. Some worked on roofing. And some worked specifically on the ducts for stoves and fans, after which one resident said it was the first time during a storm that it hadn’t rained on her while she was cooking dinner,” said Skitch Matson, who serves as PUMC’s Youth Pastor and also directs the Wesley Foundation at Princeton University.

It is making small but important differences in someone’s life that brings participants back to the program, year after year. PUMC has been sending volunteers to Appalachia for four decades. “There was a guy from Wilmington, North Carolina who had a tattoo of ASP on his calf,” said Mr. Matson, who graduated from Princeton Theological Seminary this past May. “These people are lifers. They’ve been doing it for years and years. The turnover rate is very low.”

It was hot in the town of Blountville, where the PUMC group was working. Thankfully, it rained every day. “That helped,” Mr. Matson said. “The work of construction is tedious and difficult. But being able to see the fruit of your works is important, especially for young students. You make strides, and you know the work you don’t finish will be finished by another group. It’s that type of longevity, knowing your drop in the bucket does count, that it makes a difference.”

The group prepared for the trip for eight months, learning about Appalachian culture and the poverty many residents face, along with basic construction skills and the meaning of service to others. They stayed at a local “mega church,” along with other volunteers from churches in Washington, D.C. and North Carolina.

“That’s very typical,” said Mr. Matson, who was making his first trip. “When you stay at one of these centers, you work in a county and there are usually 50 to 100 people staying there, all going to different sites. But you eat meals together and have evening gatherings. We got to listen to a folk duo from Tennessee who played for us. We went to watch fireworks in Bristol, which was nearby.”

Mr. Matson’s team worked on a wheelchair ramp for a woman whose husband had been confined to a wheelchair for two years. “She lives on a hill, with a very steep driveway. I’m 27 and I wouldn’t be able to push anybody up that hill. I don’t know how she did it,” he said. “We weren’t able to finish the project, but others will.”

The annual service project started out as a Methodist organization, but now includes groups from other denominations. Most of the volunteers come from the east coast. The idea is to get youth involved in mission work. “It’s very gratifying to know that what you’re doing is making a difference,” Mr. Matson said. “It is going to very directly change the lives of people living there. That’s what it’s about.”