All - Constructed - 1900–1909
| Colorado Governor's Mansion |
| Colton's Crossing Bridge |
| Colusa Carnegie Library |
| Comeaux House |
| Company F State Armory |
| Compton, Alma, House |
| Confederate Memorial in Peewee Valley |
| Confederate Monument in Augusta |
| Confederate Monument in Owingsville |
| Confederate Monument of Bardstown |
| Confederate Monument of Cadiz |
| Confederate Soldiers Monument |
| Congdon, Chester and Clara, Estate |
| Congregation Adath Jeshurun |
| Congregation Montefiore |
| Congregation Ohab Zedek |
| Conley's Ford Bridge |
| Conneaut Harbor West Breakwater Light |
| Connellsville Armory |
| Consolidated Ice Company Factory No. 2 |
| Convent of Mercy |
| Converse Mill |
| Conway Public Library |
| Cook County Hospital Administration Building |
| Cook, Joseph, House |
| Cook, William, House |
| Coolidge, Calvin, House |
| Coonley, Avery, School |
| Co-Operative Publishing Company Building |
| Cooper School |
| Coor-Bishop House |
| Copper River and Northwestern Railway |
| Cordner, Alexander and Nellie P., House |
| Corey House |
| Cornelia-Putnam Historic District |
| Cornelius, Charles and Theresa, House |
| Cornell Square |
| Cornland School |
| Corpus Christi R.C. Church Complex |
| Cortez High School |
| Cosmos Club |
| Cotton and Maple Streets School |
| Council Bluffs Free Public Library |
| County Bridge #45 |
| Court Tennis Building |
| Covington County Courthouse |
| Cox-Ange House |
| Cox, Angie Williams, Library |
| Craig-Flowers House |
| Cranbrook |
| Cranz, Frank F., House |
| Crawford Hill Mansion |
| Cromer's Mill Covered Bridge |
| Crowell, C. C., Jr., House |
| Crowfield Historic District |
| Cumberland County Courthouses |
| Cumberland Public Library |
| Curtis-Kittleson House |
| Curtiss, Louis, Studio Building |
| Curtis, William E., House |
| Cypress Avenue East Historic District |
| Dabney Post Office |
| Dana, George and Mary Agnes, House |
| Daniels, Charles A., School |
| Darden, Dr. J.W., House |
| Davenport Bag and Paper Company Building |
| Davey, Harvey M., House |
| Davidson, Sarah, Apartment Block |
| Davidson Windmill |
| Davies Hotel |
| Daylight Building |
| Dayton Arcade |
| Dearborn, Henry H., House |
| Dearborn School |
| DeBorgia Schoolhouse |
| Deering, Charles, Estate |
| Delafield Fish Hatchery |
| DeLamar Mansion |
| DeLaney Barn |
| Delaware and Northern Railroad Station |
| Delaware, Lackawanna and Western Railroad Station |
| Delaware Public Library |
| Del Monte Apartments |
| Delta Upsilon Fraternity House |
| Dement Printing Company |
| Denver and Rio Grande Western Railroad Depot |
| Denver Mint |
| Denver Municipal Auditorium |
| Derham Hall and Our Lady of Victory Chapel, College of St. Catherine |
| Deseret Relief Society Hall |
| Deslattes House |
| Des Moines Western Railway Freight House |
| Detwiler House |
| Dewey House |
| Dickinson (Carnegie Area) Public Library |
| Dickinson Estate Historic District |
| Dierks Building |
| Dimeling Hotel |
| District Building |
| Dobbs, Emma Olive, House |
Data from United States Park Service and Wikidata
