name        built          listed                       location               county
0        b & o railroad potomac river crossing  1894 , 1931  1978 - 02 - 14  harpers ferry , west virginia           washington
1                                 b & o bridge       ca1867  1977 - 11 - 23                    keedysville           washington
2                     bennies hill road bridge       ca1889  1979 - 06 - 27                     middletown            frederick
3                          bloomington viaduct  1851 , 1916  1976 - 11 - 21                    bloomington              garrett
4        bollman suspension and trussed bridge         1869  1972 - 10 - 18                         savage               howard
5                         bullfrog road bridge         1908  1978 - 11 - 21                      taneytown              carroll
6                           carrollton viaduct  1828 , 1829  1971 - 11 - 11                      baltimore       baltimore city
7          casselman 's bridge , national road         1813  1966 - 10 - 15                    grantsville              garrett
8                             crum road bridge       ca1880  1978 - 12 - 28                   walkersville            frederick
9                            fourpoints bridge       ca1876  1978 - 11 - 29                     emmitsburg            frederick
10              gilpin 's falls covered bridge      ca 1855  2008 - 12 - 03                     north east                cecil
11                        howard street tunnel  1890 , 1895  1973 - 07 - 02                      baltimore       baltimore city
12                      jericho covered bridge  1865 , 1937  1978 - 09 - 13         jerusalem , kingsville  baltimore , harford
13                               legore bridge  1898 - 1900  1978 - 09 - 18                      woodsboro            frederick
14                       lombard street bridge  1877 , 1974  1972 - 09 - 27                      baltimore       baltimore city
15                 loys station covered bridge       ca1860  1978 - 06 - 23                       thurmont            frederick
16                        old mill road bridge         1882  1979 - 03 - 07                    rocky ridge            frederick
17                     patterson viaduct ruins         1829  1976 - 06 - 03        catonsville , ilchester   baltimore , howard
18                    poffenberger road bridge         1878  1978 - 11 - 29                     middletown            frederick
19                   roddy road covered bridge       ca1860  1978 - 06 - 23                       thurmont            frederick
20  thomas viaduct , baltimore & ohio railroad         1835  1966 - 10 - 15                          relay   baltimore , howard
21     union arch bridge (cabin john aqueduct)         1864  1973 - 02 - 28                     cabin john           mongtomery
22                        utica covered bridge       ca1860  1978 - 06 - 23                       thurmont            frederick
23                       waverly street bridge         1892  1984 - 09 - 07                    westernport             allegany
24                            wilson 's bridge         1819  1982 - 03 - 15                     hagerstown           washington

Table as JSON:
{"name":{"0":"b & o railroad potomac river crossing","1":"b & o bridge","2":"bennies hill road bridge","3":"bloomington viaduct","4":"bollman suspension and trussed bridge","5":"bullfrog road bridge","6":"carrollton viaduct","7":"casselman 's bridge , national road","8":"crum road bridge","9":"fourpoints bridge","10":"gilpin 's falls covered bridge","11":"howard street tunnel","12":"jericho covered bridge","13":"legore bridge","14":"lombard street bridge","15":"loys station covered bridge","16":"old mill road bridge","17":"patterson viaduct ruins","18":"poffenberger road bridge","19":"roddy road covered bridge","20":"thomas viaduct , baltimore & ohio railroad","21":"union arch bridge (cabin john aqueduct)","22":"utica covered bridge","23":"waverly street bridge","24":"wilson 's bridge"},"built":{"0":"1894 , 1931","1":"ca1867","2":"ca1889","3":"1851 , 1916","4":"1869","5":"1908","6":"1828 , 1829","7":"1813","8":"ca1880","9":"ca1876","10":"ca 1855","11":"1890 , 1895","12":"1865 , 1937","13":"1898 - 1900","14":"1877 , 1974","15":"ca1860","16":"1882","17":"1829","18":"1878","19":"ca1860","20":"1835","21":"1864","22":"ca1860","23":"1892","24":"1819"},"listed":{"0":"1978 - 02 - 14","1":"1977 - 11 - 23","2":"1979 - 06 - 27","3":"1976 - 11 - 21","4":"1972 - 10 - 18","5":"1978 - 11 - 21","6":"1971 - 11 - 11","7":"1966 - 10 - 15","8":"1978 - 12 - 28","9":"1978 - 11 - 29","10":"2008 - 12 - 03","11":"1973 - 07 - 02","12":"1978 - 09 - 13","13":"1978 - 09 - 18","14":"1972 - 09 - 27","15":"1978 - 06 - 23","16":"1979 - 03 - 07","17":"1976 - 06 - 03","18":"1978 - 11 - 29","19":"1978 - 06 - 23","20":"1966 - 10 - 15","21":"1973 - 02 - 28","22":"1978 - 06 - 23","23":"1984 - 09 - 07","24":"1982 - 03 - 15"},"location":{"0":"harpers ferry , west virginia","1":"keedysville","2":"middletown","3":"bloomington","4":"savage","5":"taneytown","6":"baltimore","7":"grantsville","8":"walkersville","9":"emmitsburg","10":"north east","11":"baltimore","12":"jerusalem , kingsville","13":"woodsboro","14":"baltimore","15":"thurmont","16":"rocky ridge","17":"catonsville , ilchester","18":"middletown","19":"thurmont","20":"relay","21":"cabin john","22":"thurmont","23":"westernport","24":"hagerstown"},"county":{"0":"washington","1":"washington","2":"frederick","3":"garrett","4":"howard","5":"carroll","6":"baltimore city","7":"garrett","8":"frederick","9":"frederick","10":"cecil","11":"baltimore city","12":"baltimore , harford","13":"frederick","14":"baltimore city","15":"frederick","16":"frederick","17":"baltimore , howard","18":"frederick","19":"frederick","20":"baltimore , howard","21":"mongtomery","22":"frederick","23":"allegany","24":"washington"}}