 The southern segment of MD 146 was widened to in 1946.MD 146 from the center of Towson to the Baltimore Beltway was expanded to a divided highway concurrent with the construction of the highway's cloverleaf interchange with the Beltway between 1955 and 1958.The portions of Dulaney Valley Road and Jarrettsville Pike through the Loch Raven Reservoir reservation were originally maintained by the Baltimore City Department of Transportation since the reservoir is owned by the city of Baltimore.