Over the next day, they traced his steps: At 6:30 p.m. Thursday, he texted his mother, Janet, to say he was leaving his apartment in Narragansett.
Early Friday morning, a cell tower picked up his cellphone on Route 78 in the Lehigh Valley, "which would be his route home," Janet Royer said.
He bought gas and water around 2 a.m. at a Sunoco station on Route 100, Janet Royer said. A security camera showed him drinking water in the car, then heading south on Route 100.
"If anyone has a camera that shoots Route 29 or Route 100," we would hope they would check their film," Janet Royer said. "He drove over five and a half hours to get lost a half-hour from home."
Matthew Royer is a Perkiomen Valley High School graduate and a soccer and tennis player. He has a tight-knit group of friends, many of whom are out searching for him, his mother said.
"I can't imagine what happened to him; it's the worst nightmare," she said.
Matthew Royer was last seen wearing a beige Biltmore baseball cap, a dark-green golf shirt, khaki shorts, and flip flops. He stands 6 feet, 1 inch tall and weighs 160 pounds. He has brown hair and blue eyes.
He was driving a silver 2008 Chevrolet Cobalt with Pennsylvania license plate GZR-9059.
Anyone with information on his whereabouts is asked to call state police at 610-584-1250.
Contact Aubrey Whelan at 610-313-8112, firstname.lastname@example.org, or follow on Twitter at @aubreyjwhelan.