Built during 1840s

1841 Goshen Courthouse (Orange County, New York)
A. C. Jeffery Farmstead (Izard County, Arkansas)
A. G. Grant Homestead (Franklin County, Ohio)
A. T. Stewart Company Store (New York County, New York)
A.W. Gribble Farm (Preston County, West Virginia)
Abbot, J. T., House (Essex County, Massachusetts)
Abial Cushman Store (Penobscot County, Maine)
Abijah II O'Neall House (Montgomery County, Indiana)
Abingdon Bank (Washington County, Virginia)
Abington Farm (Anne Arundel County, Maryland)
Aborn, John, House (Middlesex County, Massachusetts)
Abraham Ulyatt House (Cuyahoga County, Ohio)
Abram W. Pike House (Kent County, Michigan)
Academy of Newark (New Castle County, Delaware)
Ackerville Baptist Church of Christ (Wilcox County, Alabama)
A historic church in Ackerville, Alabama.
Acworth Downtown Historic District (Cobb County, Georgia)
Adam Boyd House (Howard County, Arkansas)
Adam Dunlap Farmstead (Dane County, Wisconsin)
Adams Corners Schoolhouse (Putnam County, New York)
One-room schoolhouse museum, temporarily closed in Putnam Valley.
Adams Mill (Carroll County, Indiana)
Adams Street Double House (Erie County, Ohio)
Adams, Charles--Woodbury Locke House (Middlesex County, Massachusetts)
Adams-Gray House (Coshocton County, Ohio)
Adams-Taylor-McRae House (Clarke County, Mississippi)
Adlai E. Stevenson I, House (Woodford County, Illinois)
Admiral's House (New York County, New York)
Adobe Flores (Los Angeles County, California)
Afton Villa Gardens (West Feliciana Parish, Louisiana)
Ahira R. Hinkley House (Waukesha County, Wisconsin)
Ainsworth E. Blunt House (Whitfield County, Georgia)
Alabama State Capitol (Montgomery County, Alabama)
Alabama State Penitentiary (Elmore County, Alabama)
The first state prison established in Alabama.
Alanson Pomeroy House (Cuyahoga County, Ohio)
Albany Rural Cemetery (Albany County, New York)
Albany Town House (Oxford County, Maine)
Albert R. Fox House (Rensselaer County, New York)
Albert Slingerlands House (Albany County, New York)
Albion (Fairfield County, South Carolina)
19th Century plantation home near Winnsboro, SC
Albon Chase House (Clarke County, Georgia)
Alcatraz (San Francisco County, California)
Aldrich, Benjamin, Homestead (Coos County, New Hampshire)
Alexander B. Griffin House (Portage County, Ohio)
Alexander Kelly House (Moore County, North Carolina)
Alexander Moore Farm (Catawba County, North Carolina)
Alexander Taylor Rankin House (Allen County, Indiana)
Alexander Young Cabin (Washington County, Iowa)
Alexander, Arad, House (Worcester County, Massachusetts)
Alexandre Fontenot fils, House (St. Landry Parish, Louisiana)
Alfred Dockery House (Richmond County, North Carolina)
Alice Lord Goodine House (Caledonia County, Vermont)
Alkire House (Franklin County, Ohio)
All Saints Episcopal Church (Westchester County, New York)
Allcorn--Kokemoor Farmstead (Washington County, Texas)
Allegheny Baptist Church (Venango County, Pennsylvania)
Allegheny Cemetery (Allegheny County, Pennsylvania)
Allen House (De Soto Parish, Louisiana)
Allen Worley and Foushee Houses (Fayette County, Kentucky)
Allen, Nathaniel Topliff, Homestead (Middlesex County, Massachusetts)
Allen-Beville House (Queens County, New York)
Allen-Mangum House (Granville County, North Carolina)
Allison-Barrickman House (Jefferson County, Kentucky)
Alonzo Drake House (Cuyahoga County, Ohio)
Alonzo W. Olds House (Livingston County, Michigan)
Alpheus Jones House (Wake County, North Carolina)
Alpheus Truett House (Williamson County, Tennessee)
Alsop, Richard IV, House (Middlesex County, Connecticut)
Alvarado Adobe (Site) (Contra Costa County, California)
ALVIN CLARK (schooner) (Menominee County, Michigan)
Amelia Bloomer House (Seneca County, New York)
American Hotel (Schoharie County, New York)
American Printing Co. and Metacomet Mill (Bristol County, Massachusetts)
Ames Manufacturing Company (Hampden County, Massachusetts)
Amis-Bragg House (Northampton County, North Carolina)
Amite County Courthouse (Amite County, Mississippi)
Amos Lawrence House (Bennington County, Vermont)
Ancram Schoolhouse (Columbia County, New York)
Schoolhouse now a private home in Ancram.
Anderson Brothers Building (Charlottesville, Virginia)
Andrew Ferguson House (Coshocton County, Ohio)
Andrew Smyth House (Jasper County, Texas)
Andrews-Duncan House (Wake County, North Carolina)
Angels Camp (Calaveras County, California)
Angier, John B., House (Middlesex County, Massachusetts)
Ansel Clark House (Lorain County, Ohio)
Anson Davis House (Franklin County, Ohio)
Anson Grange #88 (Somerset County, Maine)
Antrim (Carroll County, Maryland)
Appleby's Methodist Church (Dorchester County, South Carolina)
Applegate--Fisher House (Hardin County, Kentucky)
Applegate-Lassen Trail (Unspecified county, Nevada)
Appomattox Historic District (Appomattox County, Virginia)
Archer House Hotel (Clark County, Illinois)
Abe Lincoln Slept Here
Archibald Smith House (Fulton County, Georgia)
Archibald Taylor Plantation House (Granville County, North Carolina)
Arden (Essex County, Massachusetts)
Armed Forces Retirement Home--Washington (Washington, District of Columbia)
Armory of the Kentish Guards (Kent County, Rhode Island)
Armstrong Academy Site (Bryan County, Oklahoma)
Armstrong House (Jackson County, West Virginia)
Armstrong House (Stewart County, Georgia)
Arnheim (Radford, Virginia)
Arnold-Simonton House (Montgomery County, Texas)
Arnot House (Harrison County, Texas)
Asa and Caroline Wing House (Oswego County, New York)
Asa Chandler House (Elbert County, Georgia)
Asa E. Young House (Barren County, Kentucky)
Asa Johnston Farmhouse (Conecuh County, Alabama)
Asa May House (Jefferson County, Florida)
Asbury Historic District (Unspecified county, New Jersey)
Asbury Methodist Episcopal Church (Wicomico County, Maryland)
Asbury United Methodist Church (Cheshire County, New Hampshire)
Ash Hill (Prince George's County, Maryland)
Ashburton House (Washington, District of Columbia)
Ashland (Bertie County, North Carolina)
Ashland (Ascension Parish, Louisiana)
Ashleigh (Fauquier County, Virginia)
Aslak Lie Cabin (Dane County, Wisconsin)
Aspen Hall (Mercer County, Kentucky)
Aspen Hill (Jefferson County, West Virginia)
Athenaeum of Philadelphia (Philadelphia County, Pennsylvania)
Athens State College Historic District (Limestone County, Alabama)
Athol (Chowan County, North Carolina)
Atlantic Avenue Tunnel (Kings County, New York)
Auburn (Caroline County, Virginia)
Auburn House (Baltimore County, Maryland)
Augusta Canal Industrial District (Richmond County, Georgia)
Augustin Grignon Hotel (Winnebago County, Wisconsin)
Former hotel now a private residence
Augustine Paper Mill (New Castle County, Delaware)
Aunty Green Hotel (Van Buren County, Iowa)
Autrey House (Lincoln Parish, Louisiana)
Avery, Thomas, House (New London County, Connecticut)
Avery-Hunter House (Licking County, Ohio)
Avon Inn (Livingston County, New York)
19th Century hotel still in operation
Avondale Mill (Prince George's County, Maryland)
Awbury Historic District (Philadelphia County, Pennsylvania)
Aycrigg Mansion (Passaic County, New Jersey)
B.F. Bissman House (Richland County, Ohio)
Bacas House (St. John the Baptist Parish, Louisiana)
Bagatelle Plantation House (Iberville Parish, Louisiana)
Bailey Graveyard (Wilson County, Tennessee)
Baite Ousley House (Union County, Tennessee)
Baker Mansion (Blair County, Pennsylvania)
Baker-Dauderstadt Farm (Somerset County, New Jersey)
Baldwin-Reynolds House (Crawford County, Pennsylvania)
Bale Mill (Napa County, California)
Bancroft and Sons Cotton Mills (New Castle County, Delaware)
Banfill Tavern (Anoka County, Minnesota)
Bank of Newark Building (New Castle County, Delaware)
Bannerman House (Pender County, North Carolina)
Bannister, Emory, House (Worcester County, Massachusetts)
demolished in 1981
Baptist Church (Des Moines County, Iowa)
Baptiste G. Aubuchon House (St. Louis County, Missouri)
Barden Cobblestone Farmhouse (Yates County, New York)
Barleywood (Jefferson County, West Virginia)
Barlow Road (Unspecified county, Oregon)
Barr House (Fairfield County, Ohio)
Barret House (Richmond, Virginia)
Barrett-Faulkner House (Anson County, North Carolina)
Barrows-Scribner Mill (Cumberland County, Maine)
Barton Hall (Colbert County, Alabama)
Bass--Morrell House (Giles County, Tennessee)
Bass-Perry House (Russell County, Alabama)
Bassett Family House (Otsego County, New York)
Batchelder, Alden, House (Middlesex County, Massachusetts)
Bates-Cockrem House (Erie County, Ohio)
Bates-Geers House (Texas County, Missouri)
Battersea (Hale County, Alabama)
A historic plantation house in Prairieville, Alabama.
Battery Weed (Richmond County, New York)
Bay Settlement Church and Monument (Delaware County, Iowa)
Bayouside (Rapides Parish, Louisiana)
Bazore Mill (Pickaway County, Ohio)
Beal, Persia, House (Cheshire County, New Hampshire)
Bear's Mill (Darke County, Ohio)
Beard, Josiah, House (Middlesex County, Massachusetts)
Beardsley Avenue Historic District (Elkhart County, Indiana)
Bearse, Capt. Oliver, House (Barnstable County, Massachusetts)
Burned in 2011, and since demolished.
Beasley--Parham House (Williamson County, Tennessee)
Beauchamp-Newman House (Wirt County, West Virginia)
Bechelbronn (Lunenburg County, Virginia)
Beckley Furnace (Litchfield County, Connecticut)
Beebe Hill School (Litchfield County, Connecticut)
One-room schoolhouse built in 1850's after previous building destroyed by fire, in Falls Village.
Beech Grove Cemetery (Delaware County, Indiana)
Beers and St. John Company Coach Inn (Muscatine County, Iowa)
Bell Farmhouse (New Castle County, Delaware)
Bell House (Knox County, Ohio)
Belle Aire (Roanoke County, Virginia)
Belle Alliance (Assumption Parish, Louisiana)
Belleview (New Castle County, Delaware)
Bellevue (Leon County, Florida)
Bellevue (Campbell County, Kentucky)
Bellevue (Prince George's County, Maryland)
Bellevue Cemetery (Essex County, Massachusetts)
Bellinger-Dutton House (Schoharie County, New York)
Belmead (Powhatan County, Virginia)
Belmont Club/John Young House (Bristol County, Massachusetts)
Belmont Hall (New Castle County, Delaware)
Belvidere Hill Historic District (Middlesex County, Massachusetts)
Bemis Mill (Middlesex County, Massachusetts)