Iowa - Criteria: A (event)
| 100 Block of West Broadway Historic District |
| Abraham Lincoln High School |
| Adair County Democrat-Adair County Free Press Building |
| Adams County Jail |
| Adel Public Square Historic District |
| Akron Opera House |
| Albia Square and Central Commercial Historic District |
| Alden Public Library |
| Algona Junior and Senior High School Building and High School Building Annex |
| Allamakee County Courthouse |
| Allamakee County Court House |
| Alleman, Richard L. and Verda M., Farm Historic District |
| Allen, James, Stone Barn |
| Amana Villages |
| Ambrose Hall |
| American House |
| American Legion Memorial Building |
| American School of Wild Life Protection Historic District |
| Ames High School |
| Ames Main Street Historic District |
| Anamosa Main Street Historic District |
| Andrews, Josiah, House |
| Antioch School |
| Antlers Hotel |
| Appanoose County Sheriff's House and Jail |
| Apperson-Iowa Motor Car Company Building |
| Architecture of Henry K. Holsman Historic Campus District |
| Armour Creameries Poultry House |
| Armstrong, George and Susan Guiberson, House |
| Ashby Manor Historic District |
| Atlantic High School |
| Audobon County Court House |
| Audubon County Courthouse |
| Audubon County Home Historic District |
| Avery Theater, The |
| Ayrshire Apartments |
| Backbone State Park Historic District |
| Bailey, William H. and Alice, House |
| Baker, C. H., Double House |
| Bandshell Park Historic District |
| Bank of Sumner |
| Baptist Church |
| Bartlett, Walter M., Double House |
| Bates Park Historic District |
| Baxter, H.A., Coal Company Historic District |
| Bay Settlement Church and Monument |
| Beach School |
| Beaconsfield Supply Store |
| Beck, Chief Justice Joseph M., House |
| Bedford Commercial Historic District |
| Bedford Oil Company Station |
| Beeds Lake State Park, Civilian Conservation Corps Area |
| Beers and St. John Company Coach Inn |
| Belle Plaine Main Street Historic District |
| Bell, Hill McClelland, House |
| Bell, John, Block |
| Benjamin Chapel and Richwoods Cemetery |
| Bennett Building |
| Bennington No. 4 |
| Benton County Courthouse |
| Bentonsport |
| Berry, Dr. William E. and Ethel Rosenberger, House |
| Best Oil and Refining Company Service Station |
| Bethany Danish Evangelical Lutheran Church |
| Bethel African Methodist Episcopal Church |
| Bethel AME Church |
| Bethel AME Church |
| Bethel Church |
| Bettendorf-Washington School |
| Bevington, C. D. and Eliza Heath, Privy |
| Bevington, C. D., House and Stone Barn |
| Bicksler Block |
| Big 4 Fair Art Hall |
| Big Creek Schoolhouse |
| Birdsall Lime Kiln |
| Black Hawk County Soldiers Memorial Hall |
| Blackhawk Hotel |
| Black Hawk Hotel |
| Blackhawk State Park, Black Hawk Preserve (Area B) |
| Blackhawk State Park, Denison Beach Area (Area C) |
| Blackhawk State Park, Wildlife Preserve Area (Area A) |
| Blair House |
| Bloedel, Christian, Wagon Works |
| Bloomfield Public Library |
| Bloomfield Square |
| B'nai Jacob Synagogue |
| Bohemian Commercial Historic District |
| Bohemian Savings Bank |
| Bonaparte Historic Riverfront District |
| Bonaparte Pottery Archeological District |
| Boone Viaduct |
| Bowery Street Grocery Store |
| Boyle, Hugh and Matilda, House and Cemetery Historic District |
| Boyt Company Building |
| Brazelton House Hotel |
| Bregant, Jean and Inez, House |
| Bremer County Court House |
| Bricker-Price Block |
| Broad View Ranch Historic District |
| Brooks Round Barn |
Data from United States Park Service and Wikidata
