| Owner | Count | 1.
| Clan McLeod, Isle of Skye, Scotland | 1 | 2.
| Clancy, Fred M., Mrs., Clarks Summit, Pennsylvania | 2 | 3.
| Clancy, John, | 4 | 4.
| Clancy, John, Mr. & Mrs., New York, New York | 11 | 5.
| Clanzel T. Brown Community Center, Jacksonville, Florida | 1 | 6.
| Clapham, John H., Mr. & Mrs., Pennsylvania | 1 | 7.
| Clapp, E. Donaldson, Auburn, New York | 1 | 8.
| Clapp, Eugene & Meredith, | 2 | 9.
| Clara Barton Birthplace, North Oxford, Massachusetts | 2 | 10.
| Clara Barton National Historic Site, Glen Echo, Maryland | 12 |
|