Glen Arm
Market InsightsGlen Arm is an unincorporated community in Baltimore County, Maryland, United States.Ravenshurst was listed on the National Register of Historic Places in 1978.Glen Arm was once the home to a Grumman aircraft manufacturing plant. Today, the building serves as the American headquarters of and a warehouse for Ulla Popken women's clothing. Until 1958, this community was served by the Maryland and Pennsylvania Railroad at milepost 14.5. In 1921, at the railroad's crossing of Glen Arm Road, what generally is recognized as the nation's first train-actuated railroad crossing signal was installed by the railroad's Superintendent of Signals, Charles Adler, Jr. Adler later designed early traffic-actuated traffic lights for the City of Baltimore, and also invented the system of flashing warning lights used on aircraft.
