All - Constructed - 1900–1909
| Angelus |
| Anna-Dean Farm |
| Annamede |
| Annand-Loomis House |
| Annunciation Church |
| Ansonia Hotel |
| Ansorge Hotel |
| Anthony-Buckley House |
| Antigo Opera House |
| Antigo Public Library and Deleglise Cabin |
| Antioch Baptist Church |
| Antlers Cafe and Bar |
| Apartment at 1261 Madison Avenue |
| Appanoose County Courthouse |
| Aquinas Institute |
| Arcadia Free Public Library |
| Arch Street Bridge over the Passaic River |
| Arcola Carnegie Public Library |
| Ardmore Carnegie Library |
| Argabrite House |
| Argyle Building |
| Argyle Flats |
| Arizona Pioneers' Home |
| Arizona-Sonora Manufacturing Company Machine Shop |
| Arizona State Capitol Building |
| Arkansas State Capitol |
| Arkansas Tuberculosis Sanatorium Historic District |
| Arlington Branch Library and Fire Hall |
| Arlington Club |
| Arlington Masonic Temple |
| Arlington Methodist Episcopal Church, South |
| Arlington Pumping Station |
| Arminius Hotel |
| Armitage Herschell Carousel |
| Armory, Old,-Vermillion |
| Armour & Co. Building |
| Armour, J. Ogden, House |
| Armstrong Creek Bridge |
| Armstrong Manual Training School |
| Armstrong, W. J., Company Wholesale Grocers |
| Arnold, Benjamin Walworth, House and Carriage House |
| Arnold, Thomas P., House |
| Arroyo Grande IOOF Hall |
| Art Building |
| Artz, Welsford Parker, House |
| Ashe County Courthouse |
| Asheville School |
| Ashford House |
| Ashland Company Store |
| Asposas, James, House |
| Astor Home for Children |
| Astoria City Hall |
| Asylum Bridge |
| Atauloma Girls School |
| Atchison, Topeka and Santa Fe Railway Passenger Depot |
| Atlantic Hotel |
| Austin Dam |
| Automatic Electric Company Building |
| Avent, James Monroe, House |
| Averill, Glenn M. and Edith, House |
| Avon Apartments |
| AXA Building |
| Axtell, Dr. William H. and Frances C., House |
| Aztec Motor Company Building |
| Babington, Robert H., House |
| Babington, Thomas M., House |
| Bache, Alexander Dallas, School |
| Backs, Ferdinand, House |
| Bacon, George H., House |
| Baeten, John, Store |
| Bagby Stationhouse, Water Tanks and Turntable |
| Bailey Hall |
| Bailey House |
| Bailey, W., House |
| Baker and Lovering Store |
| Baker Congregational Church |
| Baker, Francis and Harriet, House |
| Baker, Sarah J., School |
| Balboa Pavilion |
| Balch Hotel |
| Baldwin, Thomas M., House |
| Ballard Carnegie Library |
| Ball, D. C., House |
| Ballenger Building |
| Balsam Mountain Inn |
| Baltimore & Ohio Railroad Terminal |
| BALTIMORE (tug) |
| Bancroft Tower |
| Bank of Bowdle |
| Bank of Glen Jean |
| Bank of Hominy |
| Bank of Lockport |
| Bank of Minden |
| Bank of Slaughter |
| Bank of Starbuck |
| Bank of the Metropolis |
| Bank of Ville Platte |
| Bank of Washington |
| Banta, J. V., House |
| Baraboo Chicago & North Western Depot and Division Offices |
Data from United States Park Service and Wikidata
