The rough alignment of what is now MD 7 in Baltimore and Harford counties existed by 1695 as a rudimentary road; Baltimore County ordered that the road be widened to in width to allow easy passage for carts and for bridges to replace ferries at the numerous creeks along the route. In 1717, the route from Baltimore to Elkton became part of a new overland post road between Philadelphia and Williamsburg, Virginia. The highway between Baltimore and Havre de Grace was maintained as a turnpike, the Baltimore and Havre-de-Grace Turnpike, by 1825. This turnpike later became known as the Baltimore and Philadelphia Turnpike and, after collection of tolls had ceased on the highway, the Philadelphia Road or the Post Road. The final ferry along the route to be eliminated was the Susquehanna River crossing. The first vehicular bridge was a converted railroad bridge built by the Pennsylvania Railroad in 1873, replaced with the current Amtrak bridge immediately to the north in 1904, and converted into a tolled vehicular bridge owned by several citizens of Harford and Cecil counties in 1910. The Maryland State Roads Commission purchased the bridge in 1923 and removed the tolls in 1928. In 1926, the commission double-decked the bridge to increase the bridge's capacity.