B&O Steam Locomotive Roster (Post 1900)

Last revised: September 18, 2026

The Baltimore & Ohio was never a wealthy road. It climbed where the Pennsylvania and the New York Central did not, left New York from Jersey City, and still put passenger trains on the timetable as if the dining car mattered. George H. Drury, in Guide to North American Steam Locomotives, puts the twentieth-century fleet in that light: 414 E-27 Consolidations with the firebox over the rear drivers, Q-class Mikados that included the first USRA locomotive built, 2-10-2 “Big Sixes” that were fast for the type, and thirty Baldwin 2-8-8-4 EM-1s the railroad would rather have skipped for diesels. The company that ran them is the Baltimore & Ohio. Diesels are the diesel roster. This page is the steam after 1900.

Mount Clare Shops in Baltimore bought, built, and rebuilt long after most Class Is had stopped ordering steam. Last public steam was Q-4b Mikado 421 (ex-4434) on a farewell between Cleveland and Holloway, Ohio, May 17, 1958. A few engines were still on the books at the start of 1960. The tables below follow Drury’s post-1900 class grid, including Buffalo, Rochester & Pittsburgh, Buffalo & Susquehanna, Coal & Coke, Cincinnati, Hamilton & Dayton, Cincinnati, Indianapolis & Western, and Morgantown & Kingwood power that took B&O numbers.

Baltimore and Ohio 4-6-2 5309 with a short train at North Ogden Avenue Chicago January 9 1956

Baltimore & Ohio 4-6-2 #5309 has a short train at North Ogden Avenue in Chicago on January 9, 1956. The Great Northern Chair Company is in the background. American-Rails.com collection. Class P-7, Baldwin, 1927—one of the President Pacifics, two years from the end of steam.

On this page: At a glance · A mountain road · Consolidations, Mikados, Big Sixes · Old Maude to the EM-1s · Pacifics, Presidents, experiments · May 17, 1958 · Roster: switchers · Roster: freight · Roster: articulateds · Roster: passenger

At a glance

Item	Detail
Railroad	Baltimore & Ohio. Mark BO. Company Baltimore & Ohio
This roster	Classes built since 1900, after Drury, pages 73–77, including absorbed BR&P, B&S, CH&D, CI&W, Coal & Coke, and M&K power
Shops	Mount Clare, Baltimore. Also Cumberland, Grafton, Willard
Freight backbone	197 E-24 Consolidations (Pennsy H6 copies, 1902–04); 414 E-27s, 1905–10; Q-class Mikados from 1911, including USRA Q-3 4500
Big Sixes	31 class S 2-10-2s, 1914; 125 S-1s, Baldwin and Lima, 1923–26, 64-inch drivers
Articulateds	First U.S. Mallet: 0-6-6-0 Old Maude, Alco 1904. Then 0-8-8-0s, 2-8-8-0s, BR&P 2-6-6-2s, SAL 2-6-6-4s, thirty EM-1 2-8-8-4s
Passenger	P-class Pacifics, twenty P-7 Presidents of 1927, USRA light P-5s. Hudsons and the 4-4-4-4 Emerson were experiments
Last public steam	May 17, 1958. Q-4b 421, Cleveland–Holloway. Remnants on the roster into 1960
Survivors (notable)	Q-3 4500 and P-7 5300 President Washington at the B&O Railroad Museum. No EM-1. No Big Six

Roster follows Drury, Guide to North American Steam Locomotives (revised edition), pages 73–77, with Q-1c 4220–4329 added from the Mikado class page. Brooks, Schenectady, Pittsburgh, Richmond, Rhode Island, and Cooke in the builder column are Alco works. Information compiled September 18, 2026.

A mountain road that still ordered steam

By 1900 the main ran from Philadelphia through Baltimore and Washington to Cumberland. There it split: one route to Chicago via Pittsburgh and Akron, the other to St. Louis via Cincinnati. The original line, Grafton to the St. Louis main through Wheeling and Newark, Ohio, met the Chicago line at Chicago Junction, later Willard. Leonor F. Loree took control in 1901 and spent money on double track and easier grades. Pennsylvania control ended in 1906. Daniel Willard became president in 1910. In the next two decades the map filled out: Coal & Coke, Elkins to Charleston; pieces of the Cincinnati, Hamilton & Dayton and the Cincinnati, Indianapolis & Western; the Chicago & Alton; the Buffalo, Rochester & Pittsburgh and the Buffalo & Susquehanna on January 1, 1932.

Coal was the largest commodity. It was never the coal volume of the Chesapeake & Ohio or the Norfolk & Western. Helpers were standard over Sand Patch between Cumberland and Connellsville, and over the grades west of Cumberland toward Grafton and Parkersburg. Mount Clare could take a Mikado or a Pacific boiler and make a Mountain. That culture, and a fuel that came off B&O sidings, kept steam in the shops after the FTs of 1942–43. The recession of the late 1950s did what policy had not: traffic fell, and the diesels could move what was left.

E-24s, 414 E-27s, then Mikados and Big Sixes

Freight outgrew the Mogul before 1900. Two late batches of ten 2-6-0s each, 1911 and 1917, were Chicago switchers that looked like close-coupled 0-6-0s with a lead truck. First Consolidations had come in 1873; the last new ones in 1910. Compounds were in vogue at the turn of the century: 39 E-18s and 111 Camelback E-19s from Baldwin. Under Pennsylvania influence, 1902–04, came 197 class E-24s, duplicates of Pennsy H6s. Then the fleet: 414 class E-27s, Schenectady and Richmond, 1905–10. Number 2500 was the first. The firebox sat over the rear pair of drivers. Many later became L-class 0-8-0s at Mount Clare. The class survey is B&O 2-8-0s.

Baldwin turned two E-27s into 2-8-2s in 1911–12, Q-odd 4160 and 4161, in service until 1949. At the same time it built 220 Mikes from scratch, Q-1 and subclasses, 24×32 cylinders, 205 pounds. Class Q-1c, 4220–4329 of 1913, is on the Mikado page and missing from some printed grids; those engines were gone by 1941. Q-2 was assigned to eight Lima Mikes from the CI&W. Next were 100 USRA light Mikados, Q-3 4500–4599. Number 4500 was the first USRA locomotive built. It survives at the B&O Railroad Museum. Baldwin then built 135 Q-4s, 1920–23, 26×32 cylinders, 220 pounds, about 327,000 pounds on the engine. All three large classes had 64-inch drivers. In 1941–42 Mount Clare rebuilt four Q-4s with 70-inch drivers as Q-4d 4635–4637. Rather than build more of those, the railroad built Mountains. The Mikados are class Q.

Heavy grades asked for more than a 2-8-2. Class S 2-10-2s, 6000–6030, Baldwin 1914, had 58-inch drivers and worked drag. Then 125 S-1s, 6100–6224, Baldwin and Lima, 1923–26: same 30×32 cylinders, 220 pounds instead of 205, and 64-inch drivers. Most 2-10-2s were slow. The S-1s were not. Crews called them Big Sixes after the 6000 number series. They lasted into 1959 on the Toledo, Akron, and Chicago divisions after diesels took Sand Patch. None were saved. The class is Big Six.

During the war the railroad needed Pittsburgh–Chicago freight faster than the Mikes could do it. The four Q-4ds were a test. Mount Clare then built forty T-3 4-8-2s, 5555–5594, 1943–48, 70-inch drivers, cast-steel beds, boilers lengthened from old Mikados and Pacifics. Some had Vanderbilt tenders, some rectangular. In 1947 thirteen Boston & Maine Mountains became T-4 5650–5662, 73-inch drivers. The Mountains are class T.

Old Maude, 2-8-8-0s, and thirty Yellowstones

In 1904 John E. Muhlfeld, superintendent of motive power, had Alco Schenectady build America’s first Mallet, an 0-6-6-0 numbered 2400, later 7000, class DD-1. Two engines under one boiler: 20×32 high-pressure cylinders at the rear, 32×32 low-pressure at the front, 71,500 pounds tractive effort—almost twice an E-27. It went to the St. Louis World’s Fair, then to Sand Patch as a pusher, then to the hump at Willard. Long before the torch in 1938 it was Old Maude. The 0-8-8-0s that followed are class LL-1.

Baldwin in 1911 added a front engine to an E-24 and made a 2-6-8-0. It lasted six years and went back to a Consolidation. That experiment is the 2-6-8-0 page. Schenectady then built thirty 0-8-8-0s, LL-1 7020–7049, 1911–13: 26- and 41-inch cylinders, 56-inch drivers, 105,000 pounds tractive effort. Slow and complicated. Baldwin 2-8-8-0s followed, EL-1 and EL-2 in 1916, EL-3 in 1917, EL-5 in 1919–20. Between 1927 and 1944 the railroad converted 64 of 86 2-8-8-0s to simple articulateds. Eleven LL-1s were rebuilt as 2-8-8-0s, class EL-4. Sixteen Seaboard 2-8-8-2s became EL-6 2-8-8-0s with 63-inch drivers.

BR&P brought fifty-five 2-6-6-2s that became KK-4 7500–7554, and nine 2-8-8-2s that became EE-2 7316–7324. In 1947 ten Seaboard 2-6-6-4s, 69-inch drivers, became KB-1 7700–7709. Crews liked them. The last new articulateds were thirty simple 2-8-8-4 EM-1s, Baldwin, 1944–45, 7600–7629, later 650–679 in the 1950s renumber. Drury’s verdict is the one the photographs remember: they were modern, and they were not what the B&O wanted. The War Production Board was still rationing diesels. None survive. The class is EM-1; the type is Yellowstone.

Pacifics, twenty Presidents, and the experiments

Last new Ten-Wheelers were 1901: nine B-17 and thirty-five B-19 Vauclain compounds from Baldwin, thirty-five B-18 cross-compounds from Rhode Island. All three classes were simplified within a few years. Atlantics replaced Americans on the easier grades. Six A-class Vauclain compounds of 1900 became simple A-1s in 1904. Twenty A-2s from Schenectady in 1903 copied Pennsylvania E3as. Twenty-five A-3s came from Baldwin in 1910. Three Buffalo & Susquehanna Atlantics lasted; two of them ran until 1948 on a piece of line the 1942 floods had cut off from the rest of the railroad.

The Pacific was the B&O passenger engine. Hudsons and the first Mountains were experiments; later Mountains were fast freight. First Pacifics, class P, thirty-five from Schenectady in 1906, 74-inch drivers, inboard piston valves, Stephenson gear, numbered 2100–2134, then 5000–5034, then some into the 5150s. Baldwin P-1s of 1911 were the mainstay; classification through P-1a, P-1aa, and P-1ba, and conversions from Mikados, is a tangle best left on the class page. CH&D Pacifics became P-2. Then the Teens batches: thirty P-3s, ten P-4s with Vanderbilt tenders, thirty USRA light P-5s, fifteen P-6s. In 1927 Baldwin delivered twenty P-7s, 5300–5319, for Washington–New York after Reading power had handled the trains east of Philadelphia. Olive green, red and gold, named for the first twenty-one presidents (one engine stood for both Adamses). They were USRA heavy Pacifics in all but the lettering. 5300 President Washington is at the museum. Four later wore Otto Kuhler streamlining for the Cincinnatian. The Pacifics are class P.

Mount Clare’s experimental streak is the rest of the passenger column. J-1 4-4-4 Lady Baltimore, 1934, and V-2 4-6-4 Lord Baltimore, 1935, were lightweight steam for the restyled Royal Blue. They lost to Electro-Motive boxcab 50. V-1, V-3, and V-4 were one-off Hudsons. T 5500–5501 of 1925–26 were the first Mountains, 5500 carrying the Lord Baltimore name until the Hudson took it. T-1 5510 (watertube firebox) and T-2 5550 (conventional) were Baldwin 1930 tests for George Emerson. In 1937 Mount Clare built 4-4-4-4 N-1 5600, the George H. Emerson, first duplex in the country. Cylinders under the firebox overheated. Scrapped 1950. The type is duplex drive.

May 17, 1958

One of the first Alco-GE-Ingersoll-Rand boxcab switchers went to work in 1925. EMC 50 arrived in 1935. Ten two-unit passenger diesels followed in 1937–40. Six four-unit FTs came in 1942–43. Steam still came out of Mount Clare: T-3s through 1948, EM-1s the railroad had not asked for. GP7s and F7s then ate the West End, the Big Sixes, the Presidents. The 1950s renumbering shoved remaining steam into low numbers to free the 4000s and 5000s for diesels. Q-4b 4434 became 421 and pulled the last public steam train, Cleveland to Holloway, May 17, 1958. Drury notes engines still on the roster at the beginning of 1960. That is a paper date. Fire had gone out in 1958. The diesels that replaced this fleet—EA 51 on the Capitol Limited, FTs, F3s, F7s, Geeps, and the second-generation GP30s after C&O control—are the diesel roster.

Switchers

L-1 and L-2 0-8-0s were Mount Clare rebuilds from E-24 and E-27 Consolidations. D-44 390–394 are five ex-BR&P F3 0-6-0s; one of that BR&P class is displayed at Bellevue, Ohio. USRA 0-6-0s, D-30, lasted into 1956.

Type	Class	Numbers	Qty	Builder	Built	Retired	Notes
0-4-0	C-13	76, 77	2	Baldwin	1902	1948
0-4-0T	C-16	96–99	4	Baldwin	1912	1944–1951
0-6-0	D-29	91–94	4	Pittsburgh	1900–01	1930	Ex-CH&D
0-6-0	D-35	330–332	3	Cooke	1902	1928	Ex-CI&W
0-6-0	D-36	333–335	3	Brooks	1905	1934	Ex-CI&W
0-6-0	D-37	336–338	3	Brooks	1901	1934	Ex-CI&W
0-6-0	D-38	339–343	5	Lima	1916	1934	Ex-CI&W
0-6-0	D-30	350–369	20	Baldwin	1919	1956	USRA
0-6-0	D-30	370–389	20	Alco	1919	1956	USRA
0-6-0	D-44	390–394	5	Brooks	1904	1954	Ex-BR&P F3 152–156
0-8-0	L-2 through L-2c	600–714	115	B&O	1924–1941	1959	Rebuilt from E-27 2-8-0s
0-8-0	L-4, L-4a	772–789	18	Brooks	1918, 1923	1956–1958	Ex-BR&P F4 520–537
0-10-0	U	950, 951	2	B&O	1926–27	1953
0-8-0	L-1, L-1a	1000–1085	86	B&O	1923–1929	1959	Rebuilt from E-24 2-8-0s
0-6-0	D-7	1137–1176	40	Richmond, Baldwin	1901, 1903	1948
0-6-0	D-23	1180–1184	5	Baldwin	1906	1947	Camelback
0-6-0	D-12	1197	1	Richmond	1925	1953

Freight (rigid)

Number blocks were reused after the 1932 BR&P and B&S takeovers. A 3100 in 1904 is not a 3100 after those Consolidations left. Q-1c 4220–4329 is from the Mikado encyclopedia; Drury’s printed grid jumps from Q-1b to Q-3.

Type	Class	Numbers	Qty	Builder	Built	Retired	Notes
2-8-0	E-37	413	1	Baldwin	1906	1936	Ex-M&K
2-8-0	E-38	414	1	Baldwin	1918	1939	Ex-M&K
2-8-0	E-39	415, 416	2	Baldwin	1903	1947	Ex-M&K
2-8-0	E-40	417–422	6	Baldwin	1907, 1909	1938	Ex-M&K
2-8-0	E-41	425–434	10	Baldwin	1916	1950	Ex-CI&W
2-8-0	E-43	436	1	Baldwin	1900	1929	Ex-CI&W
2-8-0	E-44	437, 438	2	Alco	1901	1929	Ex-CI&W
2-8-0	E-45	439	1	Alco	1905	1934	Ex-CI&W
2-6-0	K-16	901–910	10	Baldwin	1911	1949	Chicago transfer
2-8-0	E-29	1706–1721	16	Brooks	1905	1937	Ex-CH&D
2-8-0	E-30	1722–1736	15	Baldwin	1905	1954	Ex-CH&D
2-8-0	E-32	1737–1740	4	Baldwin	1904–05	1929	Ex-Coal & Coke
2-8-0	E-19	1771–1779, 1800–1899	109	Baldwin	1900–01	1935	Camelback compound
2-8-0	E-18	1900–1938	39	Baldwin	1900	1936	Compound
2-8-0	E-19	1939, 1940	2	Baldwin	1900	1935	Compound
2-8-0	E-23	1955–1958	4	Schenectady	1902	1925
2-8-0	E-19aa	1959–1965	7	Baldwin	1903	1935	Simple
2-8-0	E-24	2200–2397	197	Richmond, Pittsburgh, Rogers	1902–04	1956	Pennsy H6 copies
2-6-0	K-17	2441–2450	10	Lima	1917	1954	Chicago transfer
2-8-0	E-27	2500–2913	414	Schenectady, Richmond	1905–10	1959	Many rebuilt to L-2 0-8-0s
2-8-0	E-31	2914–2933	20	Brooks	1910	1957	Ex-CH&D
2-8-0	E-33	2934–2945	12	Baldwin	1903–06	1950	Ex-Coal & Coke
2-8-0	E-34	2946–2949	4	Baldwin	1912–13	1950	Ex-Coal & Coke
2-8-0	E-35	2950, 2951	2	Baldwin	1914	1950	Ex-Coal & Coke
2-8-0	E-36	2952, 2953	2	Baldwin	1916	1950	Ex-Coal & Coke
2-8-0	E-52 through E-58	3010–3096	83	Baldwin, Brooks	1901–09	1950	Ex-BR&P
2-8-0	E-60, E-60a	3100–3142	42	Brooks, Pittsburgh	1904–12	1957	Ex-B&S
2-8-2	Q-1	4000–4159	160	Baldwin	1911	1956
2-8-2	Q-odd	4160, 4161	2	Baldwin	1911–12	1949	Rebuilt from 2-8-0s
2-8-2	Q-2	4162–4169	8	Lima	1916	1950	Ex-CI&W
2-8-2	Q-1b	4170–4219	50	Baldwin	1912	1956
2-8-2	Q-1c	4220–4329	110	Baldwin	1913	1941	From the Mikado class page; omitted on some printed grids
2-8-2	Q-4, Q-4a, Q-4b	4400–4499, 4600–4634	135	Baldwin	1920–23	1959	Last public steam was Q-4b 421, ex-4434
2-8-2	Q-3	4500–4599	100	Baldwin	1918	1959	USRA light. 4500 first USRA locomotive; preserved
2-8-2	Q-4d	4635–4637	3	B&O	1941–42	1955	70-inch drivers, rebuilt from Q-4s
2-8-2	Q-10	4700–4747	48	Brooks	1912–17	1959	Ex-BR&P Z 400–447
2-10-2	S	6000–6030	31	Baldwin	1914	1953	58-inch drivers
2-10-2	S-1	6100–6224	125	Baldwin, Lima	1923–26	1959	Big Sixes. 64-inch drivers
2-10-0	Y	6500–6507	8	Brooks	1907, 1909	1951	Ex-BR&P

Articulateds

Old Maude was 2400 at the 1904 fair and at the Fair of the Iron Horse in 1927; the later system number is 7000. EL-4s were LL-1 0-8-8-0s given a lead truck. KK-2 7450 is a Baldwin 1930 one-off kept from the live table; Drury’s printed grid lists KK-1 and KK-4 only.

Type	Class	Numbers	Qty	Builder	Built	Retired	Notes
0-6-6-0	DD-1	2400 / 7000	1	Schenectady	1904	1938	Old Maude. First U.S. Mallet
0-8-8-0	LL-1	7020–7049	30	Schenectady	1911–13	1950
2-8-8-0	EL-4	7020–7049	11	B&O	1919–23	1950	Rebuilt from LL-1
2-8-8-0	EL-1	7100–7114	15	Baldwin	1916	1954
2-8-8-0	EL-3	7115–7144	30	Baldwin	1917	1952
2-8-8-0	EL-5	7145–7170	26	Baldwin	1919–20	1954
2-8-8-0	EL-2	7200–7214	15	Baldwin	1916	1952
2-8-8-0	EL-6	7300–7315	16	Richmond	1917–21	1954	Ex-SAL 2-8-8-2s; simplified 1922
2-8-8-2	EE-2, EE-2a	7316–7324	9	Brooks	1918, 1923	1950–51	Ex-BR&P XX 800–808
2-6-6-2	KK-1	7400	1	Baldwin	1930	1953	Watertube firebox
2-6-6-2	KK-2	7450	1	Baldwin	1930	1953
2-6-6-2	KK-4	7500–7554	55	Schenectady, Brooks	1914–23	1951–53	Ex-BR&P LL 700–754
2-8-8-4	EM-1	7600–7629	30	Baldwin	1944–45	1960	Later 650–679. None preserved
2-6-6-4	KB-1	7700–7709	10	Baldwin	1935, 1937	1953	Ex-SAL

Passenger

P-7 5320, class P-9, was President Cleveland with Caprotti gear and a watertube boiler, rebuilt in 1945 to a standard P-7. V-2 2 / 5340 took the Lord Baltimore name from Mountain 5500 in 1935.

Type	Class	Numbers	Qty	Builder	Built	Retired	Notes
4-4-4	J-1	1 / 5330	1	B&O	1934	1949	Lady Baltimore
4-6-4	V-2	2 / 5340	1	B&O	1935	1949	Lord Baltimore
4-6-0	B-55	163	1	Baldwin	1906	1947	Ex-M&K
4-6-0	B-56	164	1	Baldwin	1909	1946	Ex-M&K
4-6-0	B-57	165–170	6	Schenectady	1916	1938	Ex-CI&W
4-6-0	B-58	171–180	10	Baldwin	1916	1953	Ex-CI&W
4-4-0	G-18	630	1	Baldwin	1903	1936	Ex-M&K
4-4-0	H-12	717, 718	2	Baldwin	1905	1929	Ex-Coal & Coke
4-4-0	M-3	862, 863	2	Baldwin	1906	1936	Ex-Coal & Coke
4-4-0	M-4	864	1	Baldwin	1912	1924	Ex-Coal & Coke
4-4-0	M-5	865–867	3	Brooks	1904	1930	Ex-CI&W
4-4-0	M-6, M-6a	868, 869	2	Alco	1904, 1906	1929–30	Ex-CI&W
4-6-0	B-17	1328–1336	9	Baldwin	1901	1935	Vauclain compound
4-4-2	A-3	1424–1449	25	Baldwin	1910	1944
4-4-2	A, A-1	1450–1455	6	Baldwin	1900–01	1929	Vauclain compound; simplified as A-1
4-4-2	A-2	1456–1475	20	Schenectady	1903	1923, 1947	Pennsy E3a copies
4-4-2	A-9	1484, 1485	2	Schenectady	1904	1948	Ex-B&S. Isolated after 1942 floods
4-4-2	A-10	1486	1	Brooks	1906	1936	Ex-B&S
4-4-2	A-6	1487, 1488	2	Brooks	1901	1937	Ex-BR&P
4-4-2	A-7	1489–1491	3	Brooks	1901	1936	Ex-BR&P
4-4-2	A-8, A-8a	1492–1496	5	Brooks	1906, 1909	1937	Ex-BR&P
4-6-0	B-18	2000–2034	35	Rhode Island	1901	1950s	Cross-compound, later simple
4-6-0	B-19	2035–2069	35	Baldwin	1901	1934	Vauclain compound
4-6-2	P	5000–5034	35	Schenectady	1906	1950	First B&O Pacifics
4-6-4	V-1	5047	1	B&O	1933	1950
4-6-2	P-2	5095–5099	5	Schenectady	1910	1948	Ex-CH&D
4-6-2	P-3	5100–5129	30	Baldwin	1913	1950
4-6-2	P-4	5130–5139	10	Baldwin	1917	1952	Vanderbilt tenders
4-6-2	P-17	5140–5148	9	Brooks	1912–13	1953	Ex-BR&P
4-6-2	P-18	5185–5192	8	Brooks	1918	1953	Ex-BR&P
4-6-2	P-8	5196–5199	4	Alco	1924	1952	Ex-CI&W
4-6-2	P-5	5200–5219	20	Baldwin	1919	1953	USRA light
4-6-2	P-5	5220–5229	10	Schenectady	1919	1956	USRA light
4-6-2	P-6	5230–5244	15	Baldwin	1922	1949	Vanderbilt tenders
4-6-2	P-19	5260–5264	5	Brooks	1923	1953	Ex-BR&P WW-2
4-6-2	P-7	5300–5319	20	Baldwin	1927	1958	Presidents. 5300 preserved
4-6-2	P-9	5320	1	B&O	1928	1956	President Cleveland. Caprotti, watertube; rebuilt 1945 to P-7
4-6-4	V-3	5350	1	B&O	1935	1950
4-6-4	V-4	5360	1	B&O	1936	1950
4-8-2	T	5500, 5501	2	B&O	1925, 1926	1953	5500 first named Lord Baltimore
4-8-2	T-1	5510	1	Baldwin	1930	1951	Watertube firebox
4-8-2	T-2	5550	1	Baldwin	1930	1952
4-8-2	T-3	5555–5594	40	B&O	1943–48	1960	Boilers from old Mikes and Pacifics
4-4-4-4	N-1	5600	1	B&O	1937	1950	George H. Emerson. First duplex
4-8-2	T-4	5650–5662	13	Baldwin	1935–40	1958	Ex-Boston & Maine

Sources

Drury, George H. Guide to North American Steam Locomotives, revised edition. Waukesha: Kalmbach Books, 2015. Pages 73–77, B&O post-1900 class grid and narrative
Edson, William D. Steam Locomotives of the Baltimore & Ohio: An All-Time Roster. Potomac: William D. Edson, 1992
Mainey, David. Baltimore & Ohio Steam in Color. Scotch Plains: Morning Sun Books, 2001
Reynolds, Kirk, and David Oroszi. Baltimore & Ohio Railroad. Osceola: MBI Publishing, 2000
Staufer, Alvin F., and Lawrence W. Sagle. Baltimore & Ohio Steam and Electric Locomotives
American-Rails class pages: Q Mikados (Q-1c 4220–4329; Q-10 into 1959; 4500 preserved); P Pacifics (5300); Big Sixes; EM-1; LL-1 / Old Maude; Emerson; T Mountains; E Consolidations
Leonard, Richard. B&O Q-4 4434 / 421, last steam passenger May 17, 1958, Cleveland–Holloway
Live American-Rails post-1900 B&O steam tables (March 13, 2025), retained as the starting grid and corrected as listed above