Just before 1 a.m. on a Sunday, Christina Nelson is driving to meet Violet, the foster puppy she and her family will take in for the foreseeable future. The puppy, Violet, is one of many dogs rescued from high-kill shelters in the South by Underhound Railroad.

A group of friends formed the organization in 2009 with a mission of rescuing dogs from euthanization in Connecticut shelters. Over time, the mission expanded to overcrowded shelters in southern states, including Georgia and North Carolina.

Renee Coombs, of Bristol, started working with Underhound Railroad in 2011 after losing her own dog to illness.

“Losing a dog is incredibly hard, and I remember I said I’m never doing this again,” Coombs said.

Hope Cruser, the former director of Underhound Railroad, asked Coombs if she would be willing to foster dogs with the organization. Soon thereafter, Coombs fostered her first dog. She is now the director of the organization.

“It never gets old,” Coombs said. “It can be stressful and frustrating, but at the same time, you know that you’re saving their lives.”

Each Underhound Railroad rescue begins with a phone call or an email from a shelter with dogs scheduled for euthanization. The call can come at any time of day, sometimes less than an hour before the dog is to be put down, Coombs said.

In order for Underhound Railroad to intervene, the dog must be able to be placed in a home, Coombs said.

Once Underhound Railroad makes the decision to save a dog, a foster family in the same state as the shelter will take the dog out of the shelter and bring it to a veterinarian for a full check-up and vaccinations. The dog will stay with the foster in the South until an individual or family is available in the North.

My Buddy’s Coming Home Pet Transport brings the dogs from the South to Scarborough, typically arriving after midnight, Coombs said. Sometimes foster families pick up dogs in Scarborough, while others continue their trip north.

When Christina Nelson and her daughter, Casey, picked up their dog at Skip Cahill Tire in Edgecomb, they also picked up three other puppies to deliver to fosters waiting in the municipal parking lot of Damariscotta. Underhound Railroad has a network of foster families stretching as far north as Calais, Coombs said.

Tom and Christina Nelson, of Damariscotta, and their children, Cameron, Abby, and Casey, have fostered almost 20 dogs since they started volunteering with Underhound Railroad almost two years ago. Casey, a seventh-grader at Great Salt Bay Community School, created a scrapbook with pages dedicated to each of the dogs and their time with the family.

“They really become a part of the family when they’re here,” Christina Nelson said. “We treat them just like we treat our own dogs, because while they’re here, they are.”

Foster families like the Nelsons help to reacquaint the dogs to life outside a shelter, a crucial step before adoption. Coombs is currently fostering a dog who is afraid of the television and of squeaky toys.

“The requirement is to provide a loving, safe home,” Christina Nelson said. “And these dogs might not know what that is.”

In addition to socializing with the family’s two dogs, the Nelsons also bring any dogs they foster to events at Lincoln Academy, where Cameron and Abby Nelson go to school, to help the dogs adapt. “It can be a lot of work, but it’s so rewarding,” Abby Nelson said.

One of the misconceptions about Underhound Railroad is that foster families often adopt the dogs. While foster families have been known to adopt a dog they have forged a connection with, more often than not, the dogs find their forever home someplace else.

“People say, ‘Oh, I couldn’t foster because I would want to keep them all,’ but you really wouldn’t,” said Tara Chase, Underhound Railroad’s adoption coordinator. “At the end of the day, you want these dogs to have a better life, and that might be with someone else.”

That knowledge, however, doesn’t always make it easy to give up the dogs.

“It’s always the hardest part, letting them go,” Casey Nelson said.

Coombs, Chase, and all foster families are volunteers. Underhound Railroad is a nonprofit and completely dependent on donations in order to continue its mission.

“Any money we make from adoption fees goes right into vet bills or transporting more dogs,” Chase said.

Foster families pay for food, flea and tick treatments, and collars for the puppies they foster.

“We tell all our fosters to be prepared to provide everything they would for their dog,” Coombs said.

The organization sometimes receives assistance from local businesses, including Ames True Value Hardware Supply in Wiscasset, which donates dog food for foster families, Coombs said.

“We’re really fortunate we have such an awesome network of support,” Coombs said. “We wouldn’t be able to do this without them.”

Currently, Underhound Railroad is providing foster homes for 30 dogs. In May, a litter of 11 puppies in need of foster homes will arrive in Maine.

“We’re always looking for fosters, volunteers, and donations so we can help more dogs,” Coombs said. “It’s a real passion, and we want to just do as much as we can.”

For more information about Underhound Railroad, go to underhoundrailroad.org or find Underhound Railroad on Facebook.