 In 1883 the Baltimore and Ohio Railroad agreed to complete the South Branch Railway Company 's planned rail line between Green Spring on the Baltimore and Ohio Railroad 's main line and Romney . Construction of the rail line began immediately . Completed in 1884 , it spanned a length of 16 @.@ 29 miles ( 26 @.@ 22 km ) . The original southern terminus of the Baltimore and Ohio Railroad 's South Branch line and the Romney Depot were built at the southern end of Depot Valley , around which Valley developed . The South Branch line formally opened for traffic on September 1 , 1884 . It was at this time that Depot Valley received its name from the Romney Depot . The Baltimore and Ohio Railroad continued to operate the South Branch line and later acquired the property outright by deed on November 20 , 1912 . 
