Question: What is the population of the county where a current National Historic landmark in Maryland was built in 1830 ?

text: List of National Historic Landmarks in Maryland
Current NHLs
Map all coordinates using : OpenStreetMap Download coordinates as : KML · GPX The NHLs are distributed over 17 of Maryland 's 23 counties and its one county-equivalent , the independent city of Baltimore . For consistency , places are listed by their National Historic Landmark program names .
This is a List of National Historic Landmarks in Maryland. There are currently 74 National Historic Landmarks (NHLs) in Maryland. Also included are short lists of former NHLs and of other historic sites of national importance administered by the National Park Service.
Landmark name Date designated Location County Description
1 Accokeek Creek Site July 19 , 1964 ( # 66000909 ) Accokeek 38°41′46″N 77°03′07″W / 38.696028°N 77.051833°W / 38.696028 ; -77.051833 ( Accokeek Creek Site ) Prince George 's Archaeological site of a palisaded village occupied from ca . A.D. 1300 to ca . 1630
2 Army Medical Museum and Library January 12 , 1965 ( # 66000854 ) Silver Spring 39°00′32″N 77°03′14″W / 39.008889°N 77.053889°W / 39.008889 ; -77.053889 ( Army Medical Museum and Library ) Montgomery This listing presently encompasses a US military medical records and research collection that dates to the 1860s . The original building in Washington , D.C. was demolished in 1969 ; the collection is now principally with the National Museum of Health and Medicine . The landmark designation is undergoing review
3 BALTIMORE ( Tug ) November 4 , 1993 ( # 93001613 ) Baltimore 39°16′22″N 76°36′01″W / 39.27270°N 76.60027°W / 39.27270 ; -76.60027 ( BALTIMORE ( Tug ) ) City of Baltimore Oldest steam-powered tugboat in operation in the United States
4 Baltimore and Ohio Transportation Museum and Mount Clare Station September 15 , 1961 ( # 66000906 ) Baltimore 39°17′01″N 76°37′57″W / 39.28352°N 76.63240°W / 39.28352 ; -76.63240 ( Baltimore and Ohio Transportation Museum and Mount Clare Station ) City of Baltimore Part of oldest American railyard ; site of first passenger rail service and first telegraph message . Collections of 19th- and 20th-century artifacts related to America 's railroads ; 250 pieces of railroad rolling stock ; 15,000 artifacts ; four nineteenth-century buildings , including the historic roundhouse ; a mile of historic track . Larg
5 Clara Barton House January 12 , 1965 ( # 66000037 ) Glen Echo 38°58′03″N 77°08′28″W / 38.96756°N 77.14114°W / 38.96756 ; -77.14114 ( Clara Barton House ) Montgomery Home of Clara Barton ; American pioneer teacher , nurse , and humanitarian ; founder of the American Red Cross
6 Bollman Truss Railroad Bridge February 16 , 2000 ( # 72000582 ) Savage 39°08′05″N 76°49′31″W / 39.134722°N 76.825278°W / 39.134722 ; -76.825278 ( Bollman Truss Railroad Bridge ) Howard Sole surviving example of the first successful all-metal bridge design to be adopted and consistently used on a railroad
7 Brice House April 15 , 1970 ( # 70000259 ) Annapolis 38°58′45″N 76°29′14″W / 38.97917°N 76.48722°W / 38.97917 ; -76.48722 ( Brice House ) Anne Arundel Preserved 18th century Georgian style brick house
8 Carrollton Viaduct November 11 , 1971 ( # 71001032 ) Baltimore 39°16′24″N 76°39′19″W / 39.27339°N 76.65529°W / 39.27339 ; -76.65529 ( Carrollton Viaduct ) City of Baltimore Oldest operating railway bridge in the world
9 Rachel Carson House December 4 , 1991 ( # 91002058 ) Silver Spring 39°02′48″N 77°00′03″W / 39.04667°N 77.00092°W / 39.04667 ; -77.00092 ( Rachel Carson House ) Montgomery House where Rachel Carson wrote her classic work Silent Spring in 1962
10 Casselmans Bridge , National Road January 29 , 1964 ( # 66000391 ) Grantsville 39°41′48″N 79°08′37″W / 39.696667°N 79.143611°W / 39.696667 ; -79.143611 ( Casselmans Bridge , National Road ) Garrett Bridge built in 1813 on the National Road , the nation 's first major public works project
11 Whittaker Chambers Farm May 17 , 1988 ( # 88001824 ) Westminster 39°39′35″N 76°58′35″W / 39.659722°N 76.976389°W / 39.659722 ; -76.976389 ( Whittaker Chambers Farm ) Carroll Farm home of Whittaker Chambers , accuser of Alger Hiss ; papers hidden here in a pumpkin led to Hiss 's conviction ; Chambers wrote Witness , his best-selling autobiography , here
12 Chase-Lloyd House April 15 , 1970 ( # 70000260 ) Annapolis 38°58′52″N 76°29′18″W / 38.98121°N 76.48838°W / 38.98121 ; -76.48838 ( Chase-Lloyd House ) Anne Arundel Three-story brick Georgian mansion dating from 1769-1774
13 Chestertown Historic District April 15 , 1970 ( # 70000263 ) Chestertown 39°12′45″N 76°04′10″W / 39.2125°N 76.069444°W / 39.2125 ; -76.069444 ( Chestertown Historic District ) Kent
14 College of Medicine of Maryland September 25 , 1997 ( # 97001275 ) Baltimore 39°17′07″N 76°37′25″W / 39.28518°N 76.62362°W / 39.28518 ; -76.62362 ( College of Medicine of Maryland ) City of Baltimore Oldest medical school building in the U.S
15 Colonial Annapolis Historic District June 23 , 1965 ( # 66000383 ) Annapolis 38°58′41″N 76°29′29″W / 38.978056°N 76.491389°W / 38.978056 ; -76.491389 ( Colonial Annapolis Historic District ) Anne Arundel NRHP 66000383 , and boundary increase NRHP 84003875 , in 1984
16 USS CONSTELLATION ( Frigate ) May 23 , 1963 ( # 66000918 ) Baltimore 39°17′03″N 76°36′42″W / 39.28426°N 76.61166°W / 39.28426 ; -76.61166 ( USS CONSTELLATION ( Frigate ) ) City of Baltimore Constructed in 1854 ; sloop-of-war , or corvette ; second United States Navy ship to carry this famous name
17 Doughoregan Manor November 11 , 1971 ( # 71000376 ) Ellicott City 39°16′36″N 76°53′35″W / 39.276667°N 76.893056°W / 39.276667 ; -76.893056 ( Doughoregan Manor ) Howard Built in 1766 ; until 1832 home of Charles Carroll , last surviving signer of the Declaration of Independence
18 EDNA E. LOCKWOOD ( Bugeye ) April 19 , 1994 ( # 86000258 ) St. Michaels 38°47′08″N 76°13′10″W / 38.78568°N 76.21941°W / 38.78568 ; -76.21941 ( EDNA E. LOCKWOOD ( Bugeye ) ) Talbot Built in 1889 ; Chesapeake Bay bugeye ; last working oyster boat of her kind
19 Ellicott City Station November 24 , 1968 ( # 68000025 ) Ellicott City 39°15′56″N 76°47′43″W / 39.26544°N 76.79529°W / 39.26544 ; -76.79529 ( Ellicott City Station ) Howard
20 First Unitarian Church November 7 , 1973 ( # 72001495 ) Baltimore 39°17′36″N 76°36′58″W / 39.29340°N 76.61611°W / 39.29340 ; -76.61611 ( First Unitarian Church ) City of Baltimore