Saint Mary - Blacksburg, Est. 1938 In Montgomery County, beginning at the juncture of the Roanoke-Montgomery County line and the Norfolk Southern rails, southwest along the Norfolk Southern rails to VA-657, follow a straight line to the end of VA-619, west on VA-619 to VA-705, west on VA-705 to VA-685, north on VA-685 to V A-652, west on VA-652 to the Montgomery-Pulaski County line, north, east, and south along the Montgomery-Pulaski, Montgomery-Roanoke County lines to the Norfolk Southern rails, which is the starting point