Northern Pacific Railway locomotives Mallet and Simple Articulated Locomotives Mallet and Simple Articulated Locomotives

| Class_ | Wheel_arrangement | Fleet_numbers | Manufacturer | Serial_numbers | Year_made | Quantity_made | Quantity_preserved |
|---|---|---|---|---|---|---|---|
| Mallet and Simple Articulated Locomotives | Mallet and Simple Articulated Locomotives | Mallet and Simple Articulated Locomotives | Mallet and Simple Articulated Locomotives | Mallet and Simple Articulated Locomotives | Mallet and Simple Articulated Locomotives | Mallet and Simple Articulated Locomotives | Mallet and Simple Articulated Locomotives |
| Z | 2-6-6-2 | 3000–3015 | Baldwin | 30566…31557 | 1907 | 16 | 0 |
| Z-1 | 2-6-6-2 | 3100–3105 | Baldwin | 34389…34483 | 1910 | 6 | 0 |
| Z-2 | 2-8-8-2 | 4000–4004 | Baldwin | 34382–34386 | 1910 | 5 | 0 |
| Z-3 | 2-8-8-2 | 4005–4025 | Alco | 52839…62472 | 1913, 1917, 1920 | 21 | 0 |
| Z-4 | 2-8-8-2 | 4500–4503 | Alco | 64373–64376 | 1923 | 4 | 0 |
| Z-5 | 2-8-8-4 | 5000 | Alco | 67578 | 1928 | 1 | 0 |
| Z-5 | 2-8-8-4 | 5000–5011 | Baldwin | 61292…61495 | 1930 | 11 | 0 |