List of largest locomotives List List

| name_ | railway | series | maker | dates | drive | wheel_arrangement | weight | power_ | notes_ |
|---|---|---|---|---|---|---|---|---|---|
| Big Boy | Union Pacific | X4000-X4024 | ALCO | 1941-–44 | Steam | 4-8-8-4 | 548 t | 6,290 horsepower (4,690 kW) | Several on static display. , No. 4014 is to be moved from Pomona, Calif., to Cheyenne, Wyo. for restoration. |
| XA Triplex | Virginian Railway | 700 | Baldwin | 1916 | Steam | 2-8-8-8-4 | 383 t | N/A, Tractive Effort: 199,560 lb simple; 166,600 lb compound | Rebuilt into separate locomotives |
| Challenger | Union Pacific | 3985 | ALCO | 1936–43 | Steam | 4-6-6-4 | 485 t | 6,200 horsepower (4,623 kW) | Operates in excursion service; largest operational steam locomotive in 2007 |
| GTEL 8500 `Big Blow` | Union Pacific | 1-30 (control cab), 1B-30B (turbine unit) | General Electric | 1958–61 | Gas turbine-electric | C-C+C-C | 425 t | 8,469 horsepower (6,315 kW) Over 10,000 hp at lower altitude and ambient temperatures. | Two preserved in museums. Most powerful internal combustion locomotive built. |