Union Pacific Steam Locomotive Wheel Arrangements
Index For This Page
This page was last updated on November 8, 2022.
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Steam locomotives on Union Pacific, like most of America's railroads, used the Whyte classification system for their wheel arrangement, named for Frederick Methvan Whyte.
(Read the Wikipedia article about the Whyte classification system for steam locomotives)
0-6-0 Class S
(Switch)
Total of 303 locomotives
UP's 303 0-6-0 S-Class switchers were built between 1890 and 1921, in the following series:
- (21) LA&SL 4226-4246 (21)
- (187) UP 4300-4307 (8), 4310-4347 (38), 4350-4480 (131), 4600-4609 (10 USRA)
- (61) OSL 4700-4544 (45), 4748-4752 (5), 4758-4763 (6), 4753-4757 (5 USRA)
- (34) OWRR&N 4900-4933 (34)
The S-51, S-55 and S-56 classes (62 total) were built before the Harriman Common Standard era, built in 1887-1902.
The S-1 to S-6 classes (226 total) were the Harriman Common Standard designs, built in 1904-1920.
The Special classes (15 total) were USRA design, built in 1918-1919.
Retirements for the pre-Harriman era locomotives started as early as 1913. The Harriman era locomotives, built beginning in 1901, were retired starting in 1925 and continued through to 4466's retirement in 1962.
Sorted by Road Number
| Class | Last Assigned Number | Qty. |
| S-56 | LA&SL 4226 (1) | 1 |
| S-55 | LA&SL 4227-4228 (2) | 2 |
| S-1 | LA&SL 4229-4234 (6) | 6 |
| S-2 | LA&SL 4235-4239 (5) | 5 |
| S-3 | LA&SL 4240-4242 (3) | 3 |
| S-6 | LA&SL 4243-4246 (4) | 4 |
| S-51 | OSL 4700-4702 (3), OSL 4725-4729 (5) | 8 |
| S-2 | OSL 4703-4724 (22), OSL 4759-4763 (5) | 27 |
| S-1 | OSL 4730-4734 (5), OSL 4758 (1) | 6 |
| S-3 | OSL 4735-4739 (5) | 5 |
| S-4 | OSL 4740-4744 (5) | 5 |
| S-5 | OSL 4748-4752 (5) | 5 |
| S-Spec. | OSL 4753-4757 (5) | 5 |
| S-51 | OWRR&N 4900-4901 (2), OWRR&N 4931-4933 (3) | 5 |
| S-2 | OWRR&N 4902-4922 (21) | 21 |
| S-4 | OWRR&N 4923-4926 (4) | 4 |
| S-1 | OWRR&N 4927-4930 (4) | 4 |
| S-51 | UP 4300-4307 (8), UP 4310-4347 (38) | 46 |
| S-1 | UP 4350-4359 (10) | 10 |
| S-2 | UP 4360-4400 (41) | 41 |
| S-4 | UP 4401-4420 (20) | 20 |
| S-5 | UP 4421-4450 (30) | 30 |
| S-6 | UP 4451-4480 (30) | 30 |
| S-Spec. | UP 4600-4609 (10) | 10 |
| 303 |
Sorted by Class
| Class | Last Assigned Number | Qty. |
| S-51 | UP 4300-4307 (8), UP 4310-4347 (38) | 46 |
| S-51 | OSL 4700-4702 (3), OSL 4725-4729 (5) | 8 |
| S-51 | OWRR&N 4900-4901 (2), OWRR&N 4931-4933 (3) | 5 |
| S-55 | LA&SL 4227-4228 (2) | 2 |
| S-56 | LA&SL 4226 (1) | 1 |
| S-1 | LA&SL 4229-4234 (6) | 6 |
| S-1 | UP 4350-4359 (10) | 10 |
| S-1 | OSL 4730-4734 (5), OSL 4758 (1) | 6 |
| S-1 | OWRR&N 4927-4930 (4) | 4 |
| S-2 | LA&SL 4235-4239 (5) | 5 |
| S-2 | UP 4360-4400 (41) | 41 |
| S-2 | OSL 4703-4724 (22), OSL 4759-4763 (5) | 27 |
| S-2 | OWRR&N 4902-4922 (21) | 21 |
| S-3 | LA&SL 4240-4242 (3) | 3 |
| S-3 | OSL 4735-4739 (5) | 5 |
| S-4 | UP 4401-4420 (20) | 20 |
| S-4 | OSL 4740-4744 (5) | 5 |
| S-4 | OWRR&N 4923-4926 (4) | 4 |
| S-5 | UP 4421-4450 (30) | 30 |
| S-5 | OSL 4748-4752 (5) | 5 |
| S-6 | LA&SL 4243-4246 (4) | 4 |
| S-6 | UP 4451-4480 (30) | 30 |
| S-Spec. | UP 4600-4609 (10) | 10 |
| S-Spec. | OSL 4753-4757 (5) | 5 |
| 303 |
0-8-0 Class S
(Switch)
| S-57 | UP 4500 |
2-6-0 Class M
(Mogul)
Total of 19 locomotives
| M-51 | 4000-4001 |
| M-57 | 4200-4208 |
| M-62 | OSL 4100-4107 |
2-8-0 Class C
(Consolidation)
Total of 542 locomotives
From 1913 on, UP owned 542 2-8-0s Consolidation-type locomotives. The locomotives were all built between 1888 and 1910, with 19 locomotives, numbers 324-358, coming from the SP in 1910. Beginning with 103 locomotives built in 1901, numbers 401-479, 510-524, and 710-718 series, all 2-8-0 locomotives purchased were built to the Harriman era Common Standard pattern.
The peak years of retirement after 1925 were in 1947, with 92 retired, and again in 1956, with 47 retired.
The last three 2-8-0s on UP were 6264, 6535, and 428. UP 428 was the last operating 2-8-0 and was retired in December 1959. The 6264 and 6535 were the former 264 and 535, renumbered during 1955 and 1956 to avoid conflict with new GP9 diesel units.
These were renumbered at the end of steam into the 6000 series
| C-51 | 100-143, OSL 500-502, 700-706 |
| C-55 | 510-524, 550-554, 707-709 |
| C-57 | 150-158, 402-499, 525-539, 710-729 |
| C-2 | 201-401, 560-622, 730-768 |
2-8-2 Class MK
(Mikado; after World War II MacArthur or MacA class)
Total of 362 locomotives
UP's 362 2-8-2 Mikado (or MacArthur) type locomotives were built between 1910 and 1921, for itself, the OSL, and the LA&SL. The total remained the same until the retirements started in 1946, except for the 2701, which was sold in 1932.
Although the total quantities didn't change, there had been some swapping between UP and its subsidiaries. In 1918 OSL sent seven locomotives to the LA&SL. In 1920 UP renumbered its USRA series. In 1923 UP sent 18 2-8-2s to the OSL, OSL sent 10 locomotives to the UP, and LA&SL sent 10 2-8-2s to the OSL.
| MK-1 | 1900-1929, 2000-2014, 2100-2140 |
| MK-2 | 1930-1949, 2015-2034, 2141-2165 |
| MK-8 | 2166-2171 |
| MK-3 | 2200-2209 |
| MK-4 | 2210-2219, |
| MK-5 | 2220-2244, 2500-2514, 2726-2732 |
| MK-6 | 2245-2259, 2700-2708 |
| MK-7 | 2260-2279, 2515-2514, 2709-2715, 2733-2735 |
| MK-8 | 2280-2294, 2311-2320, 2525-2534 |
| MK-Spec. | 2295-2314, 2535-2554 |
| MK-9 | 2295-2310 |
| MK-10 | 2555-2564, 2716-2725 |
2-10-2 Class TTT
(Two Ten Two)
Total of 144 locomotives.
| CS Class | Last Assigned Number | Qty. |
| TTT-1 | UP 5000-5006, 5008, 5009 (9), LA&SL 5525 (1) | 10 |
| TTT-2 | OSL 5300-5305 (6) | 6 |
| TTT-3 | UP 5014 (1), LA&SL 5526-5529 (4) | 5 |
| TTT-4 | UP 5015-5039 (25) | 25 |
| TTT-5 | OSL 5314-5318 (5) OWRR&N 5400-5407, 5410, 5414 (10) | 15 |
| TTT-6 | UP 5040-5089 (50), OSL 5306-5313 (8), UP 5500-5514 (15) | 73 |
| TTT-7 | UP 5515-5524 (10) | 10 |
| 144 |
4-4-0 Class E
(Eight wheeler)
From 1916 on, UP owned 88 4-4-0 American-type locomotives. All were retired by 1936, with only a single locomotive on the roster between 1933 and the final year of 1936.
| E-56 | LA&SL 1056-1057 |
| E-57 | OWRR&N 1111 |
| E-61 | OSL 1000-1001 |
| E-62 | UP 900-930, OSL 1002, 1004-1013, LA&SL 1052-1055, OWRR&N 1122-1123 |
| E-63 | OSL 1003, OWRR&N 1102-1108 |
| E-64 | OWRR&N 1114-1121 |
| E-69 | UP 931-947, LA&SL 1058-1061 |
| E-70 | LA&SL 1050 |
4-4-2 Class A
(Atlantic)
Total of 66 locomotives
UP's 66 4-4-2 Atlantic type locomotives were built between 1903 and 1911. All were retired by the end of 1933. The first group of 4-4-2s to be retired were the 14 Baldwin Vauclain compounds, retired in 1921, with the last two retired in 1923.
UP had 35 locomotives, OSL had 12, LA&SL had 4, and OWRR&N had 15.
| A-2 | UP 3300-3319, OSL 3400-3411 |
| A-3 | UP 3320-3334 |
| A-1 | LA&SL 3376-3379 |
| A-4 | OWRR&N 3500-3514 |
4-6-0 Class T
(Ten Wheeler)
Total of 306 locomotives
From 1915 on, UP owned a total of 306 4-6-0 Ten-Wheelers. Most were retired by 1946, with one still on the roster. UP 1243 was retained after the second to last Ten-Wheeler was retired in 1955, and is preserved as part of the railroad's Historical Collection at Cheyenne, Wyoming.
Four 4-6-0s (UP 1584-1587) were acquired by UP from its former subsidiary, Pacific & Idaho Northern, in 1936.
| T-1 | OWRR&N1755-1760 |
| T-2 | OSL 1572-1578, OWRR&N1742-1747 |
| T-3 | OSL 1579-1583, OWRR&N 1748-1754 |
| T-51 | OSL 1514-1529 |
| T-54 | OSL 1502 |
| T-55 | OWRR&N 1701-1708 |
| T-57 | UP 1200-1216, 1222-1225, 1227-1230, 1233-1236, 1239-1247, 1306, OSL 1500-1501, 1540-1561, 1584, 1586-1587, OWRR&N 1733-1741 |
| T-61 | UP 1250-1289, OSL 1585 |
| T-62 | UP 1226, 1311, 1319, OSL 1503-1513 |
| T-63 | UP 1360-1369, OWRR&N 1709-1726 |
| T-64 | OWRR&N 1727-1732 |
| T-68 | LA&SL 1591-1596 |
| T-69 | UP 1220-1221, 1231-1232, 1238, 1300-1305, 1307-1310, 1312-1318, 1320-1329, OSL 1534-1539 |
| T-73 | UP 1330-1347, OSL 1562-1571 |
| T-79 | UP 1348-1359 |
4-6-2 Class P
(Pacific)
Total of 209 locomotives
UP's 209 4-6-2 Pacific type locomotives were built between 1903 and 1920. The retirements began as early as 1926 and continued through 1958. UP 3203 was the last 4-6-2 on the railroad. The worst years for retirements were in 1933 (22 retired), 1934 (15 retired) and 1947 (59 retired).
In 1928, two OSL 3100s were transferred to UP 2900s.
Only 14 of the 209 4-6-2 Pacific locomotives received UP's two-tone gray passenger paint scheme. (Read more about UP's two-tone gray Pacifics)
OWRR&N 3203 was the last P-class locomotive to be retired, in January 1958; as of September 2015, being restored by the Friends of OR&N 197 at Oregon Rail Heritage Foundation in Portland, Oregon.
Classes P-1 through P-6 were classed as Light Pacific.
| P-1 | UP 2800-2818, LA&SL 3150-3170, OWRR&N 3204-3207 |
| P-2 | OWRR&N 3200-3203 |
| P-3 | UP 2819-2824, OSL 3100-3103, OWRR&N 3208-3210 |
| P-4 | UP 2825-2828, LA&SL 3173-3175 |
| P-5 | UP 2829-2848 |
| P-6 | UP 2850-2859, OSL 3104-3113, OWRR&N 3211-3217 |
Classes P-7 through P-13 were classed as Heavy Pacific.
| P-7 | OWRR&N 3218-3219 |
| P-8 | UP 2860-2869, OSL 3114-3123, LA&SL 3176-3181 |
| P-9 | UP 2870-2879, OSL 3124-3128 |
| P-10 | UP 2880-2899, 2910, OSL 3129-3133 |
| P-11 | OSL 3134-3138 (69-inch drivers) |
| P-12 | OWRR&N 3226-3227 |
| P-13 | UP 2900-2909, 2911 |
4-8-0 Class TW
(Twelve Wheeler)
Total of 15 locomotives
From 1915 on, UP owned 15 4-8-0 Twelve-Wheelers. The first five were retired in 1925 and the final locomotives were retired in 1928.
| TW-57 | UP 1800-1807 |
| TW-55 | UP 1850-1856 |
4-8-2 Class MT
(Mountain)
Total of 60 locomotives
| MT-1 | UP 7000-7039, LA&SL 7850-7864 |
| MT-2 | LA&SL 7865-7869 |
(Read more about two-tone gray and other features on UP's 7000-class 4-8-2 Mountain locomotives)
4-8-4 Class FEF
(Four Eight Four)
The 45 FEF (Four-Eight-Four) class locomotives were in three classes. The 20 FEF-1, numbers 800-819, were delivered in 1937. The 15 FEF-2 locomotives, numbers 820-834, were delivered in 1939, and the final 10 FEF-3 locomotives, numbers 835-844, were delivered in 1944, and were the last steam locomotives built new for UP.
| FEF-1 | UP 800-819 |
| FEF-2 | UP 820-834 |
| FEF-3 | UP 835-844 |
(Read more about two-tone gray and other features on UP's 800-class 4-8-4 Northern locomotives)
(Read more about the use of UP's 800-class 4-8-4 Northerns on Cajon Pass in Southern California)
4-10-2 Class FTT
(Four Ten Two)
Total of 10 locomotives
| FTT-1 | UP 8000 |
| FTT-2 | UP 8800-8808 |
4-12-2 Class UP
(Union Pacific)
Total of 88 locomotives
| UP-1 | UP 9000 |
| UP-2 | UP 9001-9014, OWRR&N 9708 |
| UP-3 | UP 9015-9029, OWRR&N 9700-9707 |
| UP-4 | UP 9030-9054 |
| UP-3 | UP 9055-9062 |
| UP-5 | UP 9063-9087, OSL 9500-9514 |
2-8-8-0 Class MC
(Mallet Compound)
Total of 70 locomotives
UP's 2-8-8-0 Articulated Consolidations were all built between 1918 and 1924 as CS Class MC (Mallet Compound) locomotives.
(Also in 1918, Utah Railway received three 2-8-8-0 locomotives, ordered in late 1916 by the Union Pacific Equipment Association. Utah Railway had asked for UP's assistance in the design of these locomotives, with Utah Railway soon to assume the operation of its own trains. UP evaluated the available designs, and determined that the design of fifteen B&O EL-series delivered in 1916 was a good match for the projected and similar service slow speed coal drags on Utah Railway. These three Utah Railway locomotives were very similar to later UP's MC-class, but were built by Baldwin and were about 12,000 pounds lighter (weight on drivers) than the sixteen locomotives delivered in 1918 to UP and OSL. Utah Railway used MC-2 as the class for their locomotives, the same as UP's class.)
Beginning in 1936 the locomotives were rebuilt from compound to simple, with a change in class, from CS Class MC to CS Class SA-C (Simple Articulated Compound). Beginning in 1937, as the rebuilding was completed, they were renumbered from the 3600 class, to the 3500 class (after the 3500-class 4-4-2 Atlantics were scrapped).
The three OSL 3700 class and three OWRR&N 3800 class locomotives were also rebuilt to simple locomotives, but retained their original numbers until 1944 when they were renumbered to the 3500 series to vacate the two number series to make way for the 4-6-6-4 locomotives.
| Class | Built | Qty. | UP | OSL | OWRR&N |
| MC-2 | 1918 | 16 | UP 3600-3614 | OSL 3703 | |
| MC-3 | 1920 | 19 | UP 3615-3633 | ||
| MC-4 | 1922 | 10 | UP 3634-3638 | OSL 3704, 3705 | OWRR&N 3803-3805 |
| MC-5 | 1923 | 5 | UP 3639-3643 | ||
| MC-6 | 1924 | 20 | UP 3645-3664 | ||
| 70 |
2-8-8-0 Class SAC
(Simple Articulated - Consolidation)
Retirements began in 1947 and continued through 1954.
| Class | Qty. | UP | OSL | OWRR&N |
| SA-C-2 | 15 | UP 3500-3514 | ||
| SA-C-3 | 25 | UP 3515-3533, UP 3544 (ex OSL 3703) | OSL 3565, 3566 | OWRR&N 3567-3569 |
| SA-C-4 | 15 | UP 3534-3538 | ||
| SA-C-5 | 5 | UP 3539-3543 | ||
| SA-C-6 | 20 | UP 3545-3564 | ||
| 70 |
2-8-8-2 Class SA
(Simple Articulated and Mallet Compounds)
| Class | Qty | UP Number |
| SA-57 | 19 | UP 3570-3588 (ex C&O H-7) |
| SA-57 | 11 | UP 3589-3599 (ex C&O H-7a) |
2-8-8-2 Class MC
(Mallet Compounds)
| Class | Qty | UP Number |
| MC-57 | 5 | UP 3670-3674 (ex N&W Y-3) |
4-6-6-4 Class CSA
(Challenger Simple Articulated)
Total of 40 locomotives
(Informally known as the "Fetters Challengers," named for their principle designer, Arthur H. Fetters, UP's Mechanical Engineer at the time)
(Known by many as the "Light Challengers," or the "Early Challengers," or the "1st Design Challengers")
| CSA-1 | UP 3900-3814 | 15 locomotives |
| CSA-2 | UP 3915-3939 | 25 locomotives |
UP 3800-3814 were built as UP 3900-3914 in 1936; renumbered to UP 3800-3814 in 1944 to clear the 3900 series for use by new 4664-5 class Challengers; renumbered to UP 3700-3714 in 1949, then back to UP 3800-3814 in 1950.
UP 3815-3839 were built as UP 3915-3939 in 1937; renumbered to UP 3815-3839 in 1944 to clear the 3900 series for use by new 4664-5 class Challengers; renumbered to UP 3715-3739 in 1949.
| No. of Locos |
Original Numbers |
Year Built |
New Class Numbers |
| 15 | 3900-3914 | 1936 | 3800-3814 |
| 25 | 3915-3939 | 1937 | 3815-3839 |
All of the Fetters Light Challengers were converted from coal to oil burners beginning in 1942. First of the series scrapped was 3834 in 1954. Last was 3806 in 1963.
(View a roster listing as 3900-class Light Challengers)
(View a roster listing as 3800-class Light Challengers)
(View a roster listing as 3700-class Light Challengers)
The Union Pacific "Light" 4-6-6-4s
(Taken from Allen Copeland's original typewritten narrative dated October 15, 1978.)
With an increase in demand for fast freight service as the U.S. pulled out of the depression, the Union Pacific started searching once again for motive power improvements. The road liked their huge 4-12-2's, particularly their speed and power, but the long rigid wheelbase and maintenance costs of the inside (third) cylinder demanded improvement.
Fifteen 4-6-6-4's, numbers 3900-3914 were purchased from the American Locomotive Company in 1936. These locomotives were the first of their wheel arrangement and were named "Challengers" by the U.P. The first group achieved all that was expected of them and another batch was delivered from ALCO in 1937, numbers 3915-3939. The 4-6-6-4's were faster than the 4-12-2's and could be used all over the system.
All locomotives were delivered as coal burners, but 3934-3939 were converted to oil fuel soon after delivery for use on the Los Angeles & Salt Lake District. The engines were made so as to be convertable from one fuel to another, requiring only the installation of a seperate oil tank in the coal bunker and oil firing jets. Each set of these Challengers differed slightly in weight, but all were similar in appearance. With semi-Vanderbuilt tenders, Walschaert valve gear, "Box-Pok" drivers and a centered headlight. The 4-6-6-4's had friction bearings on the drivers, but the lead, trailing and tender trucks had roller bearings.
The "Challengers" were considered dual service locomotives and were used in heavy passenger service as required. Early in 1943, 3900-3915 were changed to oil fuel, and in April 1944 the entire class was renumbered 3800-3839. In 1949, some of the oil burners were converted back to coal and given numbers in the 3700-series. In 1950, these coal burners were again converted to oil and reassigned their former 3800-series numbers. In 1948-49 ten of the 4-6-6-4's had the front engine frames replaced by new cast steel engine beds. Others had Commonwealth swing gate pilots, larger front sandboxes, air compressor shields and steps from the pilot up to the boiler.
The "light" Challengers (as they came to be known after heavier 4-6-6-4's were delivered in 1942-44) were initially assigned to Ogden-Green River and Ogden-Cheyenne freight service, but were soon reassigned to all parts of the far flung system, including the L.A. & S.L., O.S.L. and O.W.R.R.&N. in freight and passenger service. However, they rarely if ever ran on the Kansas Division. During the later days of steam operation, they were assigned to the Nebraska Division, running east from Cheyenne to Council Bluffs.
4-6-6-4 Class 4664
(Four Six Six Four)
Total of 65 locomotives
(Informally known as the Jabelmann Challengers, named for their principle designer, Otto Jabelmann, UP's Assistant General Superintendent of Motive Power at the time)
(Known by many as the "Late Challengers," or the "2nd Design Challengers")
| 4664-5 | UP 3930-3949 | 20 locomotives |
| 4664-3 | UP 3950-3969 | 20 locomotives |
| 4664-4 | UP 3975-3999 | 25 locomotives |
"All of the UP 4-6-6-4 Challengers were manufactured by ALCo as coal burners with the three orders of the smaller "Fetters" version 97' 10-1/2" in length; 255 lb. boiler pressure; and 69" drivers - followed by three orders of the larger "Jabelmann" version 106' 8" in length; 280 lb. boiler pressure; 69" roller bearing drivers; and with 14-wheel centipede tenders. There were a combined 105 dual purpose freight and passenger locomotives capable of speeds of 75-85 MPH in the two classes." (Robert B. Petersen, in The Streamliner, Summer 2004, Volume 18, Number 3)
Of the Jabelmann Class, 3975-3984 were converted from coal to oil burners in 1944-1946 for Pacific Coast non-coal territory. Eight of this class were converted to oil burners in 1952 due to a coal strike and renumbered as follows: 3930-3932 (3700-3702), 3934 (3703), 3937-3938 (3704- 3705), 3943-3944 (3706-3707). Last service for this class was 3713 at Cheyenne on July 23, 1959.
It was reported in June 1951 that "several" 4-6-6-4 locomotives were working in the Council Bluffs area. They were equipped with smoke lifters and had previously been assigned to passenger service out of Portland, Oregon. (The Mixed Train, Volume 1, Number 1, June 1951)
(Read more about two-tone gray and other features on UP's 3900-class 4-6-6-4 Challenger locomotives)
(View a roster listing of the 3900-class Late Challengers)
(View a roster listing of the 3700-class Late Challengers)
4-8-8-4 Class 4884
(Four Eight Eight Four) ("Big Boy")
Total of 25 locomotives
| 4884-1 | UP 4000-4019 |
| 4884-2 | UP 4020-4024 |
(View the roster listing of UP's Big Boy locomotives)
Mark Amfahr wrote about how UP used its Big Boy locomotives: "They were designed to handle trains east from Ogden, Utah to Green River, Wyoming. They were assigned to that Green River - Ogden pool for the first seven years (four yrs for the second order) of their lives. After that, they were assigned to the Cheyenne - Green River pool and worked that territory until 1957. From 1941 to 1957 they also worked other UP territories occasionally, such as Laramie-Denver, east to Sidney and North Platte, to Pocatello, west to Milford, Utah, etc., but the vast majority of their mileage was on the Wyoming Division in their pool territory. The last two years (1958-1959) they were captive to the Cheyenne - Laramie territory. I have not found evidence that a Big Boy ever worked off-line during those years." (Mark Amfahr, Trainorders.com, April 29, 2020)
"Santa Fe employee timetables from 1947 show speed and track restrictions for UP 4000s on the Santa Fe between Daggett and Riverside Junction, but there's no evidence that it ever happened when the engines were in revenue service. There were lots of active railfans in Southern California back then, including several who were railroaders on the ATSF and the UP, and I doubt if a Big Boy steaming into East LA would have escaped their notice." (Andy Sperandeo, email to UP Modelers Yahoo discussion group, January 10, 2005)
(Read about UP's 4-8-8-4 Big Boy locomotives at SteamLocomotive.com)
(Read about UP's 4-8-8-4 Big Boy Locomotives at Wikipedia.org)
Sources
Initial research completed in mid April 1996, with additional information taken from research compiled by Rick Steel, posted on August 21, 1998 to the now-defunct Streamliner email discussion group.
(This is a work in progress and information is being added on a regular basis.)
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