The predecessor highway of much of MD 34 was a 19th-century
turnpike called the Boonsboro and Sharpsburg Turnpike between the two eponymous towns via Keedysville. The modern state highway was constructed starting in 1918 with a section from Boonsboro to Keedysville. By 1921, the paved highway was extended west to the Norfolk Southern Railway west of Sharpsburg. The highway was completed to the Potomac River in 1923. MD 34 was one of the original signed Maryland state numbered highways in 1927. The state highway was relocated at its western end following the completion of a new bridge across the Potomac River in 1939. The underpass of the Norfolk Southern Railway between the Potomac River and Sharpsburg was completed around 1940. MD 34 was reconstructed from the Potomac River to Sharpsburg in 1953 and 1954. The state highway was rebuilt from Sharpsburg to Boonsboro between 1956 and 1958, including a new bridge over Antietam Creek. MD 34's bypass of Keedysville opened around 1961; the old highway through town was designated MD 845. The original river crossing at Shepherdstown was a
ford downstream from the modern bridge that had various names, including Boteler's Ford, Pack Horse Ford, Shepherdstown Ford, and Blackford's Ford. This ford was utilized by
Confederate forces in their retreat from the
Battle of Antietam. Around 1755, Thomas Swearingen started a ferry that operated through 1849, when the first covered bridge was constructed across the river. The first covered bridge was destroyed by forces under
Stonewall Jackson in 1861. A second covered bridge was constructed in 1871 and lasted until it was destroyed by the same series of floods in 1889 that
devastated Johnstown, Pennsylvania. The piers of the covered bridge remain immediately downstream from the modern bridge. An iron bridge was constructed just upstream of the present bridge. This iron bridge was destroyed in the March 1936 series of floods that
heavily damaged Pittsburgh. A high-level
Wichert continuous truss bridge was constructed at the site of the present bridge and opened July 15, 1939. The new bridge was dedicated to James Rumsey, an 18th-century pioneer of the
steamboat, who demonstrated his invention on the Potomac River at Shepherdstown in 1787. Finally, the present bridge, a steel
girder span also named for Rumsey, was constructed starting in June 2003 immediately to the north of the 1939 bridge. The new bridge opened July 15, 2005, exactly 66 years after the opening of the previous bridge, which was subsequently torn down. ==Junction list==