39°13′26″N 76°42′39″W / 39.223940°N 76.710749°W Relay, Maryland, or Relay House, Maryland, was an important junction and rail stop on the Baltimore and Ohio Railroad, located 9 miles (14 km) west of Baltimore, Maryland. It was the busiest station on the rail line except for Baltimore itself. A town grew around it: with a general store, a school, and a volunteer fire company. Currently, Relay is a historic district of Halethorpe, Maryland, with attractions like the Thomas Viaduct, the Patapsco Valley State Park,