The Bloomington Viaduct, built in 1851, is located in the Bloomington area of southeast Garrett County, just west of the Allegany County line. It is a sandstone bridge of three full center arches, each with a 56' span and a 28' rise. When first built, it carried a double track of the original Baltimore and Ohio main line across the Potomac River to Mineral County, West Virginia. In 1916 the viaduct was widened to accommodate two more tracks. The addition is a Melan-type reinforced concrete bridge of identical configuration built against the south face of the original stone bridge.
The Bloomington Viaduct was built by the Baltimore and Ohio Railroad company in 1851 as part of its original main line. The construction of the B & O through southern Garrett County spurred the growth of this region, facilitating the timber and coal industries as well as local farming. It has been said that the railroad was the most important single agent in the development of Garrett County. The B & O pioneered in the construction of multispan masonry railroad bridges such as the Bloomington Viaduct.