Nicholas Simmons, 20, disappeared from his house in Greece, New York on New Year's Day.
After his disappearance his parents Paul and Michelle Simmons contacted local authorities and launched an appeal on Facebook.
Two days later the Simmons spotted a picture of a homeless person on USA Today which they recognised as Nicholas. The picture was taken in Washington, over 450 miles away from his home town.
The picture was taken by Associated Press photographer Jacquelyn Martin and was published along with a story on cold weather sweeping across the US.
"I introduced myself and shook his hand and he would only say that his name was Nick. I told him that if I could write his whole name in the photo sometimes it could help him connect with family and he said, 'No, I'm OK, but you can just write that my name is Nick'," Martin explained.
Nicholas left his home town in a red Buick leaving all his possessions, including wallet and cell phone, behind.
Greece Capt. Patrick Phelan said: "I can't say it was a fight, but there was some type of discussion with his parents before he left the house".
After spotting the image on Sunday morning, Nicholas' sister Hannah Simmons tweeted to the USA Today reporter who wrote the story, Natalie Di Blasio: "Please contact me. You wrote an article for USA Today that features a picture of my missing brother."
By the afternoon, Nicholas' mother wrote on Facebook that the family was en route to Washington.
"God took that photo, God made us find him ... It could have been months before we had a lead on his whereabouts. My baby looks so lost and I will be spending the rest of my life making him well.
"This is by far the greatest example of God's love and divine intervention I have ever experienced. I am beyond able to put into words how I am feeling," his mother said.
Local police said there were no leads in the case until the publication of the picture.
Nicholas was taken to George Washington University Hospital for evaluation. The hospital declined to comment.
The reasons that led Nicholas to leave his house and travel up to Washington are still unclear.