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.