Sheets of United States, 1999
| Issuer | Date | Desc | State | ||
| - |  |
United States | 1/28/1999 | empty sheet (#2898) | incomplete |
| X |  |
United States | 2/18/1999 | Celebrate the Century 1940s, sheet of 15 types | |
| - | no image | United States | 2/25/1999 | empty sheet (#2899) | incomplete |
| - | no image | United States | 2/25/1999 | empty sheet (#2900) | incomplete |
| - |  |
United States | 2/25/1999 | empty sheet (#2901) | incomplete |
| - |  |
United States | 2/25/1999 | empty sheet (#2902) | incomplete |
| - |  |
United States | 2/25/1999 | empty sheet (#2903) | incomplete |
| - |  |
United States | 3/13/1999 | empty sheet (#2904) | incomplete |
| X |  |
United States | 4/6/1999 | Sonoran Desert, sheet of 10 types | incomplete |
| - |  |
United States | 4/16/1999 | empty sheet (#2905) | incomplete |
| - | no image | United States | 4/16/1999 | empty sheet (#2906) | incomplete |
| - | no image | United States | 4/16/1999 | empty sheet (#2907) | incomplete |
| - |  |
United States | 4/16/1999 | empty sheet (#2908) | incomplete |
| - | no image | United States | 4/16/1999 | empty sheet (#2909) | incomplete |
| - | no image | United States | 4/16/1999 | empty sheet (#2910) | incomplete |
| X |  |
United States | 5/26/1999 | Celebrate the Century 1950s, sheet of 15 types | incomplete |
| X |  |
United States | 9/17/1999 | Celebrate the Century 1960s, sheet of 15 types | incomplete |
| X |  |
United States | 10/1/1999 | sheet of 20 types | |
| - |  |
United States | 10/20/1999 | Christmas 1999, empty sheet (#2912) | incomplete |
| - |  |
United States | 10/20/1999 | Christmas 1999, empty sheet (#2913) | incomplete |
| - |  |
United States | 10/20/1999 | Christmas 1999, sheet of 4 types | all added |
| X |  |
United States | 11/18/1999 | Celebrate the Century 1970s, sheet of 15 types | incomplete |