ALCO PA

American Locomotive Company (ALCO)
Company type	Company
Industry	Locomotive manufacturing
Founded	January 1, 1901; 125 years ago in Schenectady, New York, United States
Headquarters	Schenectady, United States
Area served	United States, Brazil, Mexico
Key people	Ray Patten (GE engineer, designer of PA series)
Products	Diesel-electric locomotives (including ALCO PA series)

The ALCO PA series consisted of A1A-A1A diesel-electric locomotives produced through a collaboration between the American Locomotive Company (ALCO) and General Electric (GE) from 1946 to 1953 in Schenectady, New York. These cab units, designed by GE engineer Ray Patten in conjunction with the ALCO FA series, included both lead PA models equipped with cabs and cabless booster PB variants. Although the PB units were marginally shorter, they shared nearly identical mechanical components and styling. Despite their impressive appearance and power ratings between 2000 and 2250 horsepower, the PAs were noted for being less dependable than rival models such as the EMD E-unit.

ALCO intended the P series specifically for high-speed passenger service, differentiating it from the freight-focused F series. Nevertheless, numerous railroads employed both PA and FA locomotives across passenger and freight duties due to their adaptable design.

Out of the 297 locomotives manufactured, six remain today: four are preserved within museums, one PA has been refurbished for excursion purposes by Delaware-Lackawanna, and a converted PB unit continues to operate as a power car.

Service history

Two primary PA versions existed: the PA-1/PB-1, produced between September 1946 and June 1950, and the PA-2/PB-2, built from April 1950 until December 1953.

The PAs, along with their ALCO FA counterparts, originated from ALCO’s development of the Model 244 diesel engine. This project commenced in early 1944, with testing underway by November 1945. ALCO management imposed a firm deadline to release both the engine and its associated locomotives before the end of 1946.

By January 1946, testing was underway on 16-cylinder 244 engines. Although a labor strike delayed locomotive assembly, two PA units completed a month-long road trial on the Lehigh Valley Railroad in June 1946 before returning for overhauls and engine replacement.

In September 1946, the initial production batch—an A-B-A formation of PA-1s painted in Santa Fe colors (#51L, 51A, and 51B)—was showcased at New York’s Waldorf-Astoria Hotel prior to entering operational service. This set was repowered in August 1954 with EMD 16-567C engines rated at , but due to cost inefficiencies, most Santa Fe PAs retained their original 244 engines rather than undergoing repowering.

Four Santa Fe PA-1 units were sold to Delaware and Hudson Railway in 1967. Between 1974 and 1975, Morrison Knudsen rebuilt these as PA-4s, fitting them with ALCO's V-12 251 engines. While under D&H ownership, these locomotives operated on Amtrak's Adirondack route; notably, Amtrak itself never owned any PAs but instead acquired EMD E- and F-units from predecessor railroads. Subsequently, these units served with the Massachusetts Bay Transit Authority during the late 1970s and later with Ferrocarriles Nacionales de México from 1978 through 1981.

Rail enthusiasts often praised the PA as one of the most visually captivating diesel locomotives, earning it the moniker "Honorary Steam Locomotive," a term highlighted by historian Professor George W. Hilton. The locomotives were known for emitting dense black smoke during acceleration caused by turbo lag, which made them favorites among photographers.

Original proprietors

Railroad	PA1	PB1	PA2	PB2	PA1 road numbers	PB1 road numbers	PA2 road numbers	PB2 road numbers	Remarks
ALCO-GE Demonstrators			1	1			8375	8375B	Later assigned to New York Central Railroad as 4212 and 4304
ALCO-GE Demonstrators	2				9077-9078				Used for demonstration on Canadian National, painted in CN green and gold; subsequently transferred to Missouri-Kansas-Texas Railroad as PA-2 units 59A, C. These were the final PA-1 models produced.
American Freedom Train (original)	1				1776				The initial production PA1. Transferred to Gulf, Mobile and Ohio Railroad as unit 292
Atchison, Topeka & Santa Fe Railroad	28	16			51-62L, B, 70-73L	51-62A, 70-73A			Four PA1 units sold to Delaware & Hudson in 1967; these were the last to operate in the United States.
Denver & Rio Grande Western Railroad	4	2			6001, 6003, 6011, 6013	6002, 6012
Erie Railroad	12		2		850-861		862-863
Gulf, Mobile & Ohio Railroad	2				290-291
Lehigh Valley Railroad	14				601-614
Missouri-Kansas-Texas Railroad	4		8		57-58A, C		60-63A, C		Units 59A and C were ALCO PA-1 demonstrators rebuilt as PA-2s
Missouri Pacific Railroad	8		28		8001-8008		8009-8036		Units 8011 and 8012 were initially owned by International & Great Northern
New York, New Haven and Hartford Railroad	27				0760-0786				Unit 0783 was transferred to D&H in 1967 for spare parts.
New York, Chicago and St. Louis Railroad (Nickel Plate Road)	11				180-190
New York Central Railroad	4	4	4		4200-4203	4300-4303	4208-4211
Pennsylvania Railroad	10	5			5750-5759	5750B/5758B even #s
Pittsburgh and Lake Erie	4		2		4204-4207		4213-4214
Totals	169	39	81	8

International sales

The PA-2 locomotives delivered to the broad gauge Companhia Paulista de Estradas de Ferro in São Paulo State, Brazil, were equipped with a bar-style pilot and a robust horizontal steel pilot beam. One of these units has been preserved.

Preserved units

Currently, five PA locomotives and one modified PB unit remain:

Unit #600, one of the three broad gauge engines sold to Companhia Paulista, survives as a stripped shell without its prime mover or side panels. It is housed at the Companhia Paulista Museum in Jundiai, São Paulo. Although restoration efforts began in 2001, they have yet to be completed.
All four Delaware & Hudson PA-4 locomotives have been retained; two are located in the United States and two reside in Mexico.
- Between 1981 and 2000, Nos. 16 and 18 were stored in Empalme, Mexico. In 2000, preservationist Doyle McCormack and the Smithsonian Institution facilitated their return to the U.S.
  - No.16, which suffered damage from a derailment, was intended for cosmetic refurbishment to its original "Warbonnet" livery for the Smithsonian. After acquisition by the Museum of the American Railroad in 2011, it is undergoing restoration in Frisco, Texas, with the goal of reinstating its original ATSF 59L appearance.
  - No.18 has been restored as Nickel Plate Road 190 since 2002 under Doyle McCormack’s direction. Following its move to the Oregon Rail Heritage Center in Portland, restoration continued until its sale to Genesee Valley Transportation Company in March 2023 for use in excursion service. It arrived in Scranton, Pennsylvania by May 2023; mechanical work was finalized by June 2025 with a public unveiling on Delaware-Lackawanna Railroad tracks in July.
- Nos. 17 and 19 are preserved at Puebla’s National Museum of Mexican Railways. Unit DH-17 (formerly D&H #17) was painted in traditional Southern Pacific Daylight colors but had been covered with primer as of 2010.
The former Denver and Rio Grande PB-1 unit 6002 was converted into a steam generator car in 1965, fitted with Blomberg B trucks in 1980, sold to Ansco for Ski Train service near the end of 1987, and subsequently acquired by the Algoma Central Railway in 2007.

Additional Reading

Aslaksen, James and McCormack, Doyle. NKP190.com. Accessed March 26, 2005.
Hayden, Bob (ed.). Model Railroader Cyclopedia-Volume 2: Diesel Locomotives. Kalmbach Books, 1980. ISBN 0-89024-547-9.
Hollingsworth, Brian and Arthur F. Cook. The Great Book of Trains. Portland House, New York, NY, 1987. ISBN 0-517-64515-7.
Pinkepank, Jerry A. The Second Diesel Spotter's Guide. Kalmbach Publishing Co., Milwaukee, WI, 1973. ISBN 0-89024-026-4.
Romano, Andy. PA: Alco's Glamour Girl. Four Ways West Publications, 1997. ISBN 1-885614-16-0.
Stumpf, Rolf. ALCO World: Paulista RR. Accessed March 26, 2005.
Priest, Dr. Cinthia. The Santa Fe Diesel Volume One: Dieselization - 1960, pages 52–56.
UtahRails.net: Information on repowering AT&SF PA locomotives (EMD order #8506 dated August 1954).

External links

The America's PA initiative
DH-17 and DH-19 information hosted on the National Museum of Mexican Railroads site