They are travelers -- hopping freight trains, hitching rides, always in motion.
first photographed a traveler while in Las Vegas working on a street project in 2011. He spotted a man trying to hitch a ride, and he asked his cabdriver to pull over so he could take the man's picture.
"He had an interesting anchor tattoo on his face and he had a very distinct look about him for a hitchhiker," Joseph said. "He gave me 20 to 30 minutes but I never got his story."
After returning home from his trip, the photo of the hitchhiker stood out among Joseph's other images. He continued his street photography, and in Portland, Maine, he met a traveler who recognized the man with the anchor tattoo.
"I thought, 'How is it possible that you know this guy,' " Joseph said. "He told me that (the man's) name was Dickie and that he was on Facebook."
In New Orleans, Joseph met another traveler who knew Dickie, who by then had started going by Knuckles.
It was in New Orleans that Joseph learned about this culture of travelers who ride trains, form friendships, separate, and find each other again. It prompted his portrait series "Lost and Found."
Three years after Joseph first met Knuckles, the two ran into each other again at a train station in Chicago. Joseph instantly recognized Knuckles by his anchor tattoo. He then learned more about Knuckles' life, and when they saw each other again in New York, Joseph was introduced to more travelers.
A sort of wanderlust, Joseph said, drives all of the travelers he has photographed. Yet their stories vary. Some are running away from painful pasts, while others are just looking to find people they fit in with. And though some might look rough, Joseph said, they are some of the kindest and most intelligent people he has ever met.
"One girl was a valedictorian," Joseph said. "She told me: 'I had no friends until I started traveling. No one understood me. I was always bored with everything everybody else wanted to do. I didn't want to go shopping. I wanted to go out into the woods and hike, and nobody understood that.' She thinks she'll go to college eventually and become a teacher."
Freight-train hopping is illegal and very dangerous. Many of the travelers Joseph has met describe it as a high and life on the road as an addiction. One traveler likened the experience to "magic."
"They're discovering new places all the time," Joseph said. "They've seen parts of the country that we'll never see. Going to new places and meeting new people is like a high for them. There's a freedom attached to it."
Joseph said the travelers live very much by an eye for an eye, tooth for a tooth. "If you treat everyone with kindness, they'll treat you exactly the same," he said.
Because Joseph has built up a vast network of travelers, and because they all know one another, meeting new travelers is easier.
"They know they can be comfortable with me," he said. "In general, they're very open people. It's unexpected."
Joseph's portraits feel timeless. They are shot in black and white with the traveler standing before a simple background.
"There's something about it that doesn't distract the eye and makes it more about the person," he said. "I want the viewer to see the face and the person. They have this aged look, this worn look, and black and white accentuates that a little more."
Life on the road comes with a cost. With the freedom it allows, there is the opportunity to experiment with drugs and alcohol. Many travelers are young and leaving home for the first time. Traveling becomes so entwined with their identity that some feel lost when they finally stop.
"There are some people who weren't lost in the beginning (of their journey) who might be lost at the end," Joseph said.
Others, however, are much happier away from the conventions of modern society.
"They are not to be pitied nor romanticized by the viewer," Joseph said. "You want to see and feel the person who lies somewhere in between."