 Within Baltimore, MD 139 was split into a one-way pair between North Avenue and 29th Street, with northbound following Charles Street and southbound using Maryland Avenue, by 1950.In 1954, a project began to widen MD 139 from the Baltimore city line north to MD 134.In addition, preliminary work began at the site of the highway's future interchange with I-695 that year and actual construction began in 1955.