Survey No. Name (as assigned by HAER) Status Type [2] Built Documented Carries Crosses Location County Coordinates MD-1 Baltimore and Ohio Railroad, Bollman Truss Bridge Extant Bollman truss 1835 1984 Baltimore and Ohio Railroad (former) Little Patuxent River Savage Howard 39°08′05″N 76°49′31″W / 39.13472°N 76.82528°W / 39.13472; -76.82528 (Baltimore and Ohio Railroad, Bollman Truss Bridge ) MD-3 Baltimore and Ohio Railroad, Thomas Viaduct Extant Stone arch 1835 1984 CSX Capital Subdivision Patapsco River Elkridge Howard 39°13′18″N 76°42′48″W / 39.22167°N 76.71333°W / 39.22167; -76.71333 (Baltimore and Ohio Railroad, Thomas Viaduct ) MD-5 Cumberland and Pennsylvania Railroad, Wills Creek Bridge Demolished Brick arch 1860 1984 Cumberland and Pennsylvania Railroad (former) Wills Creek Cumberland Allegany 39°40′14″N 78°47′25″W / 39.67056°N 78.79028°W / 39.67056; -78.79028 (Cumberland and Pennsylvania Railroad, Wills Creek Bridge ) MD-9 Baltimore and Ohio Railroad, Carrollton Viaduct Extant Stone arch 1829 1984 CSX Baltimore Terminal Subdivision Gwynns Falls Baltimore Independent city 39°16′32″N 76°39′18″W / 39.27556°N 76.65500°W / 39.27556; -76.65500 (Baltimore and Ohio Railroad, Carrollton Viaduct ) MD-12 Baltimore and Ohio Railroad, Patterson Viaduct Ruin Stone arch 1829 1970 Baltimore and Ohio Railroad (former) Patapsco River Ilchester Howard 39°14′56″N 76°45′53″W / 39.24889°N 76.76472°W / 39.24889; -76.76472 (Baltimore and Ohio Railroad, Patterson Viaduct ) MD-16 Baltimore and Ohio Railroad, Harpers Ferry Bridge Piers Ruin 1836 1970 Baltimore and Ohio Railroad (former) Potomac River Maryland Heights, Maryland , and Harpers Ferry, West Virginia Washington County, Maryland , and Jefferson County, West Virginia 39°19′25″N 77°43′38″W / 39.32361°N 77.72722°W / 39.32361; -77.72722 (Baltimore and Ohio Railroad, Harpers Ferry Bridge Piers ) MD-22 Baltimore and Ohio Railroad, Waring Viaduct Extant Stone arch 1906 1970 CSX Metropolitan Subdivision Great Seneca Creek Gaithersburg Montgomery 39°09′32″N 77°14′53″W / 39.15889°N 77.24806°W / 39.15889; -77.24806 (Baltimore and Ohio Railroad, Waring Viaduct ) MD-23 Potomac Edison Company, Chesapeake and Ohio Canal Bridge Extant Vertical-lift bridge 1923 1970 Potomac Edison Company siding Chesapeake and Ohio Canal Williamsport Washington 39°35′59″N 77°49′36″W / 39.59972°N 77.82667°W / 39.59972; -77.82667 (Potomac Edison Company, Chesapeake and Ohio Canal Bridge ) MD-24 Salisbury Street Bridge Extant Pratt truss 1879 1970 Salisbury Street Chesapeake and Ohio Canal Williamsport Washington 39°35′57″N 77°49′35″W / 39.59917°N 77.82639°W / 39.59917; -77.82639 (Salisbury Street Bridge ) MD-31 Chesapeake and Ohio Canal, Town Creek Aqueduct Extant Stone arch 1849 1974 Chesapeake and Ohio Canal Town Creek Oldtown Allegany 39°31′24″N 78°32′39″W / 39.52333°N 78.54417°W / 39.52333; -78.54417 (Chesapeake and Ohio Canal, Town Creek Aqueduct ) MD-32 Chesapeake and Ohio Canal, Culvert 65 Extant Stone arch 1832 1974 Chesapeake and Ohio Canal Unnamed stream Dickerson Montgomery 39°11′38″N 77°28′12″W / 39.19389°N 77.47000°W / 39.19389; -77.47000 (Chesapeake and Ohio Canal, Culvert 65 ) MD-35 Poffenberger Road Bridge Extant Whipple truss 1878 1983 Poffenberger Road Catoctin Creek Middletown Frederick 39°22′54″N 77°34′18″W / 39.38167°N 77.57167°W / 39.38167; -77.57167 (Poffenberger Road Bridge ) MD-36 Old Mill Road Bridge Extant Pratt truss 1882 1983 Old Mill Road Owens Creek Rocky Ridge Frederick 39°36′07″N 77°20′19″W / 39.60194°N 77.33861°W / 39.60194; -77.33861 (Old Mill Road Bridge ) MD-37 Baltimore and Ohio Railroad, Long Bridge Demolished Trestle 1869 1983 Baltimore and Ohio Railroad (former) Antietam Creek Keedysville Washington 39°30′15″N 77°42′49″W / 39.50417°N 77.71361°W / 39.50417; -77.71361 (Baltimore and Ohio Railroad, Long Bridge ) MD-40 Keysville-Frederick County Road Bridge Replaced 1873 Keysville-Frederick County Road Monocacy River Keymar Carroll 39°39′16″N 77°16′01″W / 39.65444°N 77.26694°W / 39.65444; -77.26694 (Keysville-Frederick County Road Bridge ) MD-41 National Road, Wilson Bridge Extant Stone arch 1819 1982 National Road Conococheague Creek Hagerstown Washington 39°39′27″N 77°50′53″W / 39.65750°N 77.84806°W / 39.65750; -77.84806 (National Road, Wilson Bridge ) MD-44 Post Road Bridge Replaced Baltimore truss 1905 1984 MD 7 Northeast Corridor Havre de Grace Harford 39°32′11″N 76°06′49″W / 39.53639°N 76.11361°W / 39.53639; -76.11361 (Post Road Bridge ) MD-46 Susquehanna River Bridge Extant Pennsylvania truss 1908 1984 CSX Philadelphia Subdivision Susquehanna River Havre de Grace and Perryville Harford and Cecil 39°34′08″N 76°05′13″W / 39.56889°N 76.08694°W / 39.56889; -76.08694 (Susquehanna River Bridge ) MD-52 Sharptown Bridge Replaced Swing span 1912 1987 MD 313 Nanticoke River Sharptown Wicomico 38°32′45″N 75°43′10″W / 38.54583°N 75.71944°W / 38.54583; -75.71944 (Sharptown Bridge ) MD-53 Cabin John Aqueduct Bridge Extant Stone arch 1863 1987 MacArthur Boulevard and Washington Aqueduct Cabin John Creek Cabin John Montgomery 38°58′22″N 77°08′53″W / 38.97278°N 77.14806°W / 38.97278; -77.14806 (Cabin John Aqueduct Bridge ) MD-68 Matthews Bridge Replaced Pennsylvania truss 1914 1978 MD 146 (Dulaney Valley Road) Loch Raven Reservoir Baltimore Baltimore 39°27′46″N 76°34′50″W / 39.46278°N 76.58056°W / 39.46278; -76.58056 (Matthews Bridge ) MD-69 Chesapeake and Ohio Canal, White's Ferry Iron Bridge Abandoned Warren truss 1865 1988 White's Ferry Road Chesapeake and Ohio Canal Dickerson Montgomery 39°09′17″N 77°31′02″W / 39.15472°N 77.51722°W / 39.15472; -77.51722 (Chesapeake and Ohio Canal, White's Ferry Iron Bridge ) MD-70 Chesapeake and Ohio Canal, Iron Bridge at Lock No. 68 Abandoned Warren truss 1910 1988 Chesapeake and Ohio Canal Oldtown Allegany 39°31′50″N 78°35′17″W / 39.53056°N 78.58806°W / 39.53056; -78.58806 (Chesapeake and Ohio Canal, Iron Bridge at Lock No. 68 ) MD-71 Chesapeake and Ohio Canal, McCoy's Ferry Road Culvert Extant Stone arch 1840 1988 McCoy's Ferry Road Chesapeake and Ohio Canal Big Spring Washington 39°36′31″N 77°58′12″W / 39.60861°N 77.97000°W / 39.60861; -77.97000 (Chesapeake and Ohio Canal, McCoy's Ferry Road Culvert ) MD-72 Chesapeake and Ohio Canal, Prather's Neck Road Culvert Extant Stone arch 1840 1988 Chesapeake and Ohio Canal Neck Road Big Spring Washington MD-79 Mitchell's Mill Bridge Relocated Pratt truss 1885 1990 Carrs Mill Road Winter's Run Bel Air Harford 39°32′06″N 76°24′02″W / 39.53500°N 76.40056°W / 39.53500; -76.40056 (Mitchell's Mill Bridge ) MD-82 Stauffer Road Bridge Relocated Pratt truss 1930 1996 Stauffer Road Israel Creek Walkersville Frederick 39°28′01″N 77°20′45″W / 39.46694°N 77.34583°W / 39.46694; -77.34583 (Stauffer Road Bridge ) MD-83 Waverly Street Bridge Replaced Bowstring arch truss 1892 1991 Waverly Street George's Creek Westernport Allegany 39°29′23″N 79°02′34″W / 39.48972°N 79.04278°W / 39.48972; -79.04278 (Waverly Street Bridge ) MD-85 Governor's Bridge Extant Pratt truss 1912 1992 Governor's Bridge Road Patuxent River Bowie Prince George's and Anne Arundel 38°57′05″N 76°41′36″W / 38.95139°N 76.69333°W / 38.95139; -76.69333 (Governor's Bridge ) MD-88 Glendale Road Bridge Demolished Pennsylvania truss 1924 1992 Glendale Road Deep Creek Lake McHenry Garrett 39°30′20″N 79°18′39″W / 39.50556°N 79.31083°W / 39.50556; -79.31083 (Glendale Road Bridge ) MD-89 Hagerstown Road Bridge Relocated Pratt truss 1920 1993 Old Hagerstown Road Little Catoctin Creek Middletown Frederick 39°27′13″N 77°33′36″W / 39.45361°N 77.56000°W / 39.45361; -77.56000 (Hagerstown Road Bridge ) MD-90 Crum Road Bridge Relocated Bowstring arch truss 1890 1993 Crum Road Israel Creek Walkersville Frederick 39°28′47″N 77°19′39″W / 39.47972°N 77.32750°W / 39.47972; -77.32750 (Crum Road Bridge ) MD-92 Carderock Overpass Exant Prestressed concrete girder 1962 1994 Carderock Access Road Clara Barton Parkway Carderock Montgomery 38°58′21″N 77°11′45″W / 38.97250°N 77.19583°W / 38.97250; -77.19583 (Carderock Overpass ) MD-93 Seventy-Ninth Street Cabin John Underpass Extant Reinforced concrete rigid frame 1961 1994 Clara Barton Parkway 79th Street Cabin John Montgomery 38°58′22″N 77°09′53″W / 38.97278°N 77.16472°W / 38.97278; -77.16472 (Seventy-Ninth Street Cabin John Underpass ) MD-94 Cabin John Overpass Extant Prestressed concrete girder 1962 1994 Erricson Road Clara Barton Parkway Cabin John Montgomery 38°58′16″N 77°09′10″W / 38.97111°N 77.15278°W / 38.97111; -77.15278 (Cabin John Overpass ) MD-95 Cabin John Creek Bridge Extant Reinforced concrete box girder 1963 1994 Clara Barton Parkway Cabin John Creek Cabin John Montgomery 38°58′16″N 77°08′52″W / 38.97111°N 77.14778°W / 38.97111; -77.14778 (Cabin John Creek Bridge ) MD-96 George Washington Memorial Parkway Northbound Lane Overpass Extant Reinforced concrete rigid frame 1961 1994 Future George Washington Memorial Parkway Clara Barton Parkway Glen Echo Montgomery 38°57′46″N 77°08′09″W / 38.96278°N 77.13583°W / 38.96278; -77.13583 (George Washington Memorial Parkway Northbound Lane Overpass ) MD-97 Sycamore Island Pedestrian Overpass Extant Reinforced concrete box girder 1968 1994 Trail to Sycamore Island Clara Barton Parkway Cabin John Montgomery 38°57′31″N 77°07′54″W / 38.95861°N 77.13167°W / 38.95861; -77.13167 (Sycamore Island Pedestrian Overpass ) MD-98 Brookmont Pedestrian Overpass Extant Reinforced concrete box girder 1967 1994 Brookmont pedestrian crossing Clara Barton Parkway Glen Echo Montgomery 38°56′22″N 77°07′14″W / 38.93944°N 77.12056°W / 38.93944; -77.12056 (Brookmont Pedestrian Overpass ) MD-99 Little Falls Branch Bridge Extant Prestressed concrete girder 1961 1994 Clara Barton Parkway Little Falls Branch Glen Echo Montgomery 38°56′15″N 77°07′03″W / 38.93750°N 77.11750°W / 38.93750; -77.11750 (Little Falls Branch Bridge ) MD-100-A Suitland Parkway, Henson Creek Culvert Headwalls at Station 200 Plus 35 Extant Culvert 1944 Suitland Parkway Henson Creek Suitland Prince George's 38°50′10″N 76°53′59″W / 38.83611°N 76.89972°W / 38.83611; -76.89972 (Suitland Parkway, Henson Creek Culvert Headwalls at Station 200 Plus 35 ) MD-100-B Suitland Parkway, Henson Creek Culvert Headwalls at Station 274 Plus 50 Extant Culvert 1944 Suitland Parkway Henson Creek Suitland Prince George's 38°49′51″N 76°52′30″W / 38.83083°N 76.87500°W / 38.83083; -76.87500 (Suitland Parkway, Henson Creek Culvert Headwalls at Station 274 Plus 50 ) MD-106 Wilson Mill Bridge Replaced Parker truss 1930 1994 MD 161 Deer Creek Darlington Harford 39°37′01″N 76°12′04″W / 39.61694°N 76.20111°W / 39.61694; -76.20111 (Wilson Mill Bridge ) MD-108 Tilghman Island Bridge Relocated Rolling lift (Scherzer) bascule 1934 1998 Chesapeake Bay Maritime Museum grounds Perry Cabin Lane Saint Michaels Talbot 38°47′19″N 76°13′28″W / 38.78861°N 76.22444°W / 38.78861; -76.22444 (Tilghman Island Bridge ) \ MD-109 Proenty Road Bridge Replaced Pratt truss 1926 1994 Proenty Road Jennings Run Corriganville Allegany 39°41′29″N 78°48′13″W / 39.69139°N 78.80361°W / 39.69139; -78.80361 (Proenty Road Bridge ) MD-110 Boston Street Bridge Extant Stone arch 1902 1994 Boston Street Harris Creek Baltimore Baltimore 39°16′49″N 76°34′48″W / 39.28028°N 76.58000°W / 39.28028; -76.58000 (Boston Street Bridge ) MD-112 Weems Creek Bridge Replaced Swing span 1929 1995 MD 436 Weems Creek Annapolis Anne Arundel 38°59′34″N 76°30′28″W / 38.99278°N 76.50778°W / 38.99278; -76.50778 (Weems Creek Bridge ) MD-115 Western Maryland Railway Bridge Demolished Steel rolled stringer 1932 1995 Western Maryland Railway MD 51 Spring Gap Allegany 39°33′52″N 78°42′48″W / 39.56444°N 78.71333°W / 39.56444; -78.71333 (Western Maryland Railway Bridge ) MD-119 River Road Bridge Replaced Pratt truss 1884 1993 Casselman River Road Casselman River Grantsville Garrett 39°42′07″N 79°08′12″W / 39.70194°N 79.13667°W / 39.70194; -79.13667 (River Road Bridge ) MD-120 Harmony Road Bridge Replaced Pratt truss 1918 1996 Harmony Road Little Catoctin Creek Myersville Frederick 39°28′56″N 77°32′06″W / 39.48222°N 77.53500°W / 39.48222; -77.53500 (Harmony Road Bridge ) MD-123 Chesapeake and Ohio Canal, Conococheague Creek Aqueduct Extant Stone arch 1834 1996 Chesapeake and Ohio Canal Conococheague Creek Williamsport Washington 39°36′05″N 77°49′41″W / 39.60139°N 77.82806°W / 39.60139; -77.82806 (Chesapeake and Ohio Canal, Conococheague Creek Aqueduct ) MD-124 Allender Road Bridge Replaced Steel built-up girder 1945 1997 Allender Road CSX Philadelphia Subdivision White Marsh Baltimore 39°24′03″N 76°24′25″W / 39.40083°N 76.40694°W / 39.40083; -76.40694 (Allender Road Bridge ) MD-125 Flintville Bridge Replaced Pratt truss 1927 1998 MD 623 (Flintville Road) Broad Creek Castleton Harford 39°41′46″N 76°14′41″W / 39.69611°N 76.24472°W / 39.69611; -76.24472 (Flintville Bridge ) MD-127 Clarysville Bridge Extant Stone arch 1812 1994 National Road Braddock Run Clarysville Allegany 39°38′35″N 78°53′21″W / 39.64306°N 78.88917°W / 39.64306; -78.88917 (Clarysville Bridge ) MD-128 Little Crossings Bridge Extant Stone arch 1813 1993 National Road Casselman River Grantsville Garrett 39°41′48″N 79°08′37″W / 39.69667°N 79.14361°W / 39.69667; -79.14361 (Little Crossings Bridge ) MD-170 Bollman Truss Bridge Extant Pratt truss 2007 Westminster Carroll 39°40′02″N 77°01′01″W / 39.66722°N 77.01694°W / 39.66722; -77.01694 (Bollman Truss Bridg ) MD-174 Gilpin's Falls Covered Bridge Extant Burr truss 1860 2012 MD 272 (North East Road) (former) North East Creek North East Cecil 39°38′56″N 75°57′20″W / 39.64889°N 75.95556°W / 39.64889; -75.95556 (Gilpin's Falls Covered Bridge ) MD-180 Baltimore and Ohio Railroad, Locust Point Transfer Bridges Extant 1911 2010 Baltimore and Ohio Railroad (former) Baltimore Baltimore 39°16′29″N 76°35′20″W / 39.27472°N 76.58889°W / 39.27472; -76.58889 (Baltimore and Ohio Railroad, Locust Point Transfer Bridges ) MD-183-B Chesapeake and Ohio Canal, Big Slackwater Towpath, Pipe Culvert Extant Culvert 2005 Chesapeake and Ohio Canal towpath Unnamed stream Williamsport Washington MD-187 Jericho Road Covered Bridge Extant Burr truss 1865 2015 Jericho Road Little Gunpowder Falls Kingsville and Jerusalem Baltimore and Harford 39°27′34″N 76°23′16″W / 39.45944°N 76.38778°W / 39.45944; -76.38778 (Jericho Road Covered Bridge ) MD-190 Covered Bridge Educational Models Extant 2017 Johns Hopkins University Baltimore Baltimore 39°19′40″N 76°37′15″W / 39.32778°N 76.62083°W / 39.32778; -76.62083 (Covered Bridge Educational Models ) MD-195 Baltimore and Ohio Railroad, Metropolitan Branch Bridge 9A Relocated Steel built-up girder 1918 2019 Talbot Avenue CSX Metropolitan Subdivision Silver Spring Montgomery 39°00′07″N 77°02′41″W / 39.00194°N 77.04472°W / 39.00194; -77.04472 (Baltimore and Ohio Railroad, Metropolitan Branch Bridge 9A ) WV-36 Baltimore and Ohio Railroad, Bollman Bridge Replaced Bollman truss 1868 1987 Baltimore and Ohio Railroad (former) Potomac River Maryland Heights, Maryland , and Harpers Ferry, West Virginia Washington County, Maryland , and Jefferson County, West Virginia 39°19′27″N 77°43′43″W / 39.32417°N 77.72861°W / 39.32417; -77.72861 (Baltimore and Ohio Railroad, Bollman Bridge )