Delaware - Criteria: C (architecture/engineering)
| 901 Mt. Lebanon Rd. |
| Achmester |
| Adams, Joseph T., House |
| Aetna Hose, Hook and Ladder Company Fire Station No. 2 |
| Aiken's Tavern Historic District |
| Air Service, Inc. Hangar at Bellanca Airfield |
| Allee House |
| Allen, Charles, House |
| All Saints' Episcopal Church |
| Amstel House |
| Anderson House |
| Appoquinimink Friends Meetinghouse |
| Archmere |
| Armstrong, A., Farm |
| Armstrong Lodge No. 26, A. F. & A. M. |
| Armstrong-Walker House |
| Arnold, George, House |
| Ashland Bridge |
| Ashton Historic District |
| Aspendale |
| Attix, Thomas, House |
| Auburn Mills Historic District |
| Augustine Paper Mill |
| Baily House |
| Bancroft and Sons Cotton Mills |
| Bank House |
| Bank of Newark Building |
| Bannister Hall and Baynard House |
| Barratt Hall |
| Barratt's Chapel |
| Bartley-Tweed Farm |
| Baynard Boulevard Historic District |
| Belleview |
| Bellevue Range Rear Light Station |
| Bell Farmhouse |
| Belmont Hall |
| Belmont Hall |
| Bethel Historic District |
| Bethel Methodist Protestant Church |
| Betz, J. F., House |
| Biddle House |
| Biggs, Gov. Benjamin T., Farm |
| Blackiston, Benjamin, House |
| Blackwater Presbyterian Church |
| Bloomfield |
| Blue Hen Farm |
| Bradford-Loockerman House |
| Brandywine Manufacturers Sunday School |
| Brandywine Park |
| Brandywine Powder Mills District |
| Brandywine Village Historic District |
| Braunstein's Building |
| Brecknock |
| Breck's Mill Area |
| Brick Hotel |
| Bridgeville Historic District |
| Brindley Farm |
| Brook Ramble |
| Brown, Dr. John A., House |
| Buena Vista |
| Building at 140 W. Main Street |
| Building at 200-202A High Street |
| Building at 218 High Street |
| Building at 28-34 1/2 Academy Street |
| Building at 34 Choate Street |
| Building at High and Cannon Streets |
| Bullen, John, House |
| Burrows, W. D., House |
| Burton-Blackstone-Carey Store |
| Burton Hardware Store |
| Byrd's AME Church |
| Camden Historic District |
| Carlisle House |
| Carpenter-Lippincott House |
| Carswell, Stuart Randall & Pricilla Kellogg, House |
| Casperson, W., House |
| Center Meeting and Schoolhouse |
| Centreville Historic District |
| Chambers House |
| Chambers House |
| Chandler, Capt. Ebe, House |
| Chandler, Joseph, House |
| Chelsea |
| Cherbourg Round Barn |
| Chipman Potato House |
| Choptank |
| Choptank-Upon-The-Hill |
| Christiana Historic District |
| Church Street Historic District |
| Clark-Pratt House |
| Clayton Railroad Station |
| Clearfield Farm |
| Cleaver House |
| Cloud, Abner, House |
| Cloud-Reese House |
| Cochran Grange |
| Coleman House |
| Collins Potato House |
| Collison House |
| Cool Spring Presbyterian Church |
Data from United States Park Service and Wikidata
