 The branch extends between Frederick Junctiona wye with the Old Main Line Subdivision of CSX Transportation on the west side of the Monocacy Riverand its terminus at East Street in downtown Frederick, Maryland.The wye at Frederick Junction was the first example of its kind in the United States and is still in use today.The branch opened in December 1831 with a ceremonial train, pulled by horses, carrying directors of the B&O and various politicians from Baltimore.