USRA Light Mikado
The USRA Light Mikado was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard light freight locomotive of the USRA types, and was of 2-8-2 wheel arrangement in the Whyte notation, or 1′D1′ in UIC classification.
A total of 614 locomotives were built under the auspices of the USRA, with a further 641 copies built after the end of the USRA's control. The first, for the Baltimore and Ohio Railroad, was completed in July 1918 and given #4500. The locomotives were considered well designed and modern, and were popular and successful. Large numbers remained in service until replaced by diesel locomotives. It was also called the McAdoo Mikado after William Gibbs McAdoo, head of the USRA.
Built
With later copies, over 50 railroads used the type, including the following:| Railroad | Quantity | Class | Road numbers | Notes |
| Baltimore and Ohio Railroad | 100 | Q-3 | 4500–4599 | Built 1918 by Baldwin. Scrapped 1959. 4500 preserved. |
| Chicago and Alton Railroad | 10 | L-4 | 875–884 | Built 1918 by ALCO. To Alton Railroad 4385–4394, class Q-8. Scrapped 1941-1952 |
| Chicago and Eastern Illinois Railroad | 15 | N-2 | 1925–1939 | Built 1918 by ALCO-Schenectady. Scrapped 1942-1955. |
| Chicago Great Western Railway | 10 | L-3 | 750–759 | Built 1918 by Baldwin. Scrapped 1944-1951. |
| Chicago, Indianapolis and Louisville Railroad | 5 | J-2 | 550–554 | Built 1918 by ALCO-Schenectady. Scrapped 1947-1949 |
| Chicago, Rock Island and Pacific Railroad | 9 | K-55 | 2300–2308, 2309–2319 | Built 1919 by Baldwin And ALCO. Scrapped 1942-1945 and scrapped 1947-1951 |
| Grand Trunk Railway | 15 | M-3 | 440–454 | Built 1918 by ALCO to Canadian National Railway 3700–3714, S 2-8-2|class S-3-a]. Scrapped 1958-1959. |
| Grand Trunk Western Railroad | 25 | M-3 | 455–479 | Built 1918 by ALCO to Canadian National Railway 3715–3739, class S-3-a. Scrapped 1959-1960. 4070/3734 preserved |
| Lehigh and Hudson River Railway | 4 | 80 | 80–83 | Built 1918 by Baldwin. Scrapped 1942-1948. |
| Louisville and Nashville Railroad | 18 | J-3 | 1500–1517 | Built 1919 by Lima. Scrapped 1951-1954. |
| Maine Central Railroad | 6 | S | 621–626 | Built 1919 by ALCO. Scrapped 1953. |
| Missouri Pacific Railroad | 15 | MK-63 | 1301–1315, 1316–1325 | Built 1926 by ALCO-Brooks. Scrapped 1947-1950 |
| Monongahela Railway | 10 | L1 | 170-179 | Built 1919 by ALCO-Schenectady. Scrapped 1941-1949 |
| Nashville, Chattanooga and St. Louis Railway | 10 | L2-55 | 650–659 | Built 1918 by ALCO-Schenectady. All scrapped in 1951. |
| New York Central Railroad | 95 | H-6a | 5100–5194 | Built 1918-1919 by ALCO and Lima. Renumbered 1800–1894, less 11 to PM. Scrapped 1944-1955. |
| New York Central subsidiary Cleveland, Cincinnati, Chicago and St. Louis Railway | 25 | H-6a | 6089–6113 | Built 1918 by Baldwin. Renumbered 1700–1724. Scrapped 1944-1952. |
| New York Central subsidiary Indiana Harbor Belt Railroad | 24 | H-6a | 400–423 | Built 1918 by ALCO. 10 to SLSF, others to PM. Scrapped 1949-1950 |
| New York Central subsidiary Lake Erie and Western Railroad | 15 | H-6o | 5540–5554 | Built 1918 by Baldwin. To Nickel Plate Road 586–600. Scrapped 1947-1957. 587 preserved. |
| New York Central subsidiary Michigan Central Railroad | 20 | H-6a | 7970–7989 | Built 1918 by ALCO. Renumbered 1770–1789. Scrapped 1947-1956 |
| New York Central subsidiary Toledo and Ohio Central Railroad | 15 | H-6a | 9732–9746 | Built 1918 by ALCO. Renumbered 1732–1736. Scrapped 1945-1955 |
| New York, Chicago and St. Louis Railway | 10 | H-6a | 601–610 | Built 1918 by ALCO. Scrapped 1940-1950 |
| Pennsylvania Railroad | 20006-20038 | Built 1919 by ALCO. Refused; 10 to MP, 23 to SLSF. Scrapped 1948-1949 | ||
| Pennsylvania Railroad subsidiary Grand Rapids and Indiana Railroad | 5 | L2s | 108-112 | Built 1919 renumbered PRR 9627-9631. Scrapped 1949-1953 |
| Pere Marquette Railway | K-8 | 1011–1040 | Built 1919-1920 by ALCO and Lima. Acquired secondhand from IHB, NYC and WAB. To C&O 2350–2379 Scrapped 1952 | |
| Pittsburgh and West Virginia Railway | 3 | 1000-1002 | Built 1918 by Baldwin. Scrapped 1949-1951 | |
| Rutland Railway | 6 | H-6a | 32–37 | Built 1918 by ALCO-Schenectady. Scrapped 1951-1952 |
| Seaboard Air Line Railroad | 10 | Q-1 | 390–399 | Built 1918 by ALCO. Renumbered 490-499 in 1925. Scrapped 1954-1957. |
| St. Louis – San Francisco Railway | 4000 | 4000–4032 | Built 1919 by ALCO. Scrapped 1950-1951. 4003 and 4018 preserved. | |
| Southern Railway | 25 | Ms-1 | 4750–4774 | 4765–4775. To subsidiary Cincinnati, New Orleans and Texas Pacific Railway. Renumbered 6285–6294 in 1920 |
| Texas and Pacific Railway | H-1 | 550–560 | Refused; to Chicago, Rock Island & Pacific. | |
| Texas and Pacific Railway | 11 | H-2 | 800–810 | Built by Baldwin in 1919 |
| Union Pacific Railroad | 20 | MK-Spl | 2295–2314 | Renumbered 2480–2499 in 1920. |
| Union Pacific subsidiary Oregon Short Line Railroad | 20 | ? | 2535-2554 | Built 1918 by Baldwin. Scrapped 1945-1953 |
| Wabash Railroad | 20 | K-2 | 2201–2220 | Built 1918 by ALCO. 5 to PM, replaced by 5 from WP Scrapped 1950-1955: Wabash |
| Western Pacific Railroad | 5 | MK-55 | 321–325 | Built 1919 by Baldwin. Sold to Wabash in 1920. Scrapped 1949-1956 |
| Totals | 625 |