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EMD "SW1200" Locomotives

Last revised: December 8, 2023

By: Adam Burns

The SW1200 was pinnacle of Electro-Motive's switcher line featuring its 567 power plant.  It was the final model to feature the engine and also the most successful with a total of 1,039 units produced between 1954 and 1966.

EMD's system for designating its switchers was not consistent, particularly in the early years, which makes deciphering each models' lettering and numbering somewhat difficult.

However, the SW1200 was a straightforward moniker with "SW" denoting "switcher" and 1,200 the horsepower rating.  Once more, EMD enjoyed strong sales with this model as a variety of railroads and private industries purchased the locomotive. 

Today, just as with virtually every other model in the series, SW1200's can continue to be found hauling freight for short lines and used in industrial settings, along with also pulling excursion trains. 


962872361265423672358269026872672664.jpgNorfolk & Portsmouth Belt Line SW1200 #103 was photographed here by Joe Kmetz in Norfolk, Virginia on October 6, 1979. American-Rails.com collection.


The SW1200 began production in January, 1954 around the same time as its less powerful counterpart, the SW900. The model used EMD's 567C prime mover.

The 12-cylinder engine could produce a hefty 1,200 horsepower, which proved a strong selling point.  At this rating the locomotive could be used in either switching work or even light freight duties.  This latter ability was further enhanced by optional MU capabilities.

Using General Motors' newer model D37B traction motor the SW1200 could produce a respectable 36,000 pounds of continuous tractive effort and overall weighed just over 122-tons.  

Baltimore & Ohio SW1200 #9618 wearing the Chessie System livery is seen here at Parkersburg, West Virginia on October 13, 1976. American-Rails.com collection.

Sales for the SW1200 quickly took off and with the builder's reputation at the time as the best locomotive manufacturer on the market, sales remained steady through the 1950s and even into the 1960s.

Penn Central SW1200 #9199, still in its New Haven paint (built as #659) lays over in Maybrook, New York in the fall of 1970. Note Penn Central U25B #2672 in the background, also still in its New Haven paint (built as #2512). American-Rails.com collection.

Just as with other SW series models, numerous Class Is, short lines, and private industries purchased the switcher.  In his book, "Diesel Locomotives: Cyclopedia, Volume 2," Bob Hayden notes the SW1200 offered a variety of options including MU (as previously mentioned), sealed-beam headlight, additional rotating headlight, Flexicoil trucks, larger fuel tank, dynamic brakes, and dual controls.

Rio Grande SW1200 #135 lays over in Salt Lake City, Utah, circa 1975. Robert Eastwood, Jr. photo. American-Rails.com collection.

After EMD released the SW9 it abandoned cataloging its cow/calf TR series although it contemplated doing so with the SW900 of 1953 but ultimately decided against doing so.

In any event, the SW1200 would also not be offered in a cow/calf variant mostly because interest in the setup had waned following the SW9.

Domestic production on the switcher continued through May, 1966 and when the last unit was outshopped some 733 units (including a Great Northern rebuild) had been produced in the United States while another 274 were built by General Motors Diesel of London, Ontario (sometimes referred to as the SW1200RS).

99123842365723578238962871389609.jpgMilwaukee Road SW1200 #711 (built as #2037) - the only switcher to wear the company's "Milwaukee II" livery - works the Miller Job at the Muskego Yard in Milwaukee, Wisconsin during March, 1985. R.W. Brown photo. American-Rails.com collection.

There were also another 32 units built for export in South and Central America including Brazil, Panama, and Chile.

Beginning with the SW1000, EMD swapped engines for the newer model 645 prime mover.  In doing so the builder changed the carbody by featuring a hood with harder lines and less beveling, wider cab, and higher profile for improved visibility. 

Data Sheet and Specifications

Entered Production1/1954 (Milwaukee Road #1637-1642)
Years Produced (U.S.)1/1954 - 5/1966
Years Produced (Canada)9/1955 - 6/1964
EMD ClassSW1200
Engine567C (12 Cylinder)
Engine BuilderEMD/GM
Length44' 5"
Height (Top Of Rail To Top Of Cab)14' 6 1/2"
Width9' 11 1/2"
Weight245,000 Lbs
Fuel Capacity600 Gallons
Air CompressorWXO (Gardner-Denver)
Air Brake Schedule26L (Westinghouse)
Truck TypeGRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A) or Flexicoil
Truck Wheelbase8' 0"
Wheel Size40"
Traction MotorsD37B (4), EMD/GM
Traction GeneratorD15C, EMD/GM
Auxiliary GeneratorEMD/GM
MU (Multiple-Unit)Optional
Dynamic BrakesOptional
Gear Ratio62:15
Tractive Effort/Starting74,000 Lbs
Tractive Effort/Continuous36,000 Lbs at 11.0 mph
Top Speed65 mph

Production Rosters

Electro-Motive (EMD)

(Total Built = 732)

Owner Road Number Serial Number Order Number Completion Date Quantity
Milwaukee Road1637-164218758-1876342411/19546
Wisconsin Central (Soo Line)2120-212219085-1908742891/19553
Southern Pacific (Texas & New Orleans)113-11819486-1949142552/19546
Aliquippa & Southern12011952942826/19541
Bauxite & Northern111953042786/19541
Oliver Iron Mining Company9401953142728/19541
Aliquippa & Southern1202-120319532-1953342826/19542
Oliver Iron Mining Company941-94219534-1953542728/19542
Wheeling Steel125419536428710/19541
Oliver Iron Mining Company9431953742728/19541
Soo Line32119538428812/19541
Oliver Iron Mining Company944-94519539-1954042728/19542
Soo Line322-32419541-19543428812/19543
Coos Bay Lumber Company1201-120319661-1966342778/1954-9/19543
Milwaukee Road2048-206120041-20054428411/195414
Milwaukee Road2020-204720055-20082428611/1954-12/195428
Florida East Coast229-23520088-20094428512/19547
Soo Line325-32720108-2011042881/19553
Wisconsin Central (Soo Line)2123-212720115-2011942891/19555
Soo Line3282018242881/19551
Northern Pacific127-12920320-2032242907/1955-8/19553
Northern Pacific119-12120328-2033042913/19553
Northern Pacific122-12520331-2033442923/19554
Northern Pacific1262033542933/19551
Weyerhaeuser Timber3042035442942/19551
Chicago & Illinois Midland182036342954/19551
Wheeling Steel1250, 1255-125720364-2036742965/19554
Wheeling Steel1258-125920368-2036942995/19552
Chicago & Illinois Midland192037542954/19551
Grand Trunk Western7017-701920381-2038343004/19553
Grand Trunk Western1505-150820413-2041642705/1955-6/19554
Chicago, Burlington & Quincy9271-928020543-2055243029/1955-10/195510
Woodward Iron Company522063243078/19551
Simpson Logging Company12002063443094/19561
Simpson Logging Company12012063543405/19561
Aliquippa & Southern1204-120720636-2063943105/1955-8/19554
Tooele Valley Railway1002064043115/19551
Terminal Railroad Association Of St. Louis1219-122620656-2066343137/1955-10/19558
Illinois Terminal775-78620666-20677431611/1955-12/195512
Chicago & Illinois Midland20-2320678-20681431711/19554
Rockdale, Sandow & Southern Railroad820702431810/19551
Point Comfort & Northern Railway420703431910/19551
Ashley, Drew & Northern17621016432512/19551
Northern Pacific1302101943271/19561
Norfolk & Portsmouth Belt Line101-10521021-21025432812/1955-2/19565
Norfolk & Portsmouth Belt Line106-11521056-2106543293/1956-6/195610
Great Lakes Steel392108243325/19561
Northern Pacific133-13421100-2110143354/19562
Northern Pacific131-13221102-2110343384/19562
New Haven640-64921165-2117443341/1956-2/195610
Northern Pacific135-14021175-2118043356/1956-7/19566
Northern Pacific1412118143587/19561
Patapsco & Back Rivers125-12621242-2124343364/19562
Northern Pacific142-14421433-2143543587/19563
Bellefonte Central56242147143396/19561
New Haven650-65921473-2148243342/1956-3/195610
Aliquippa & Southern1208-121021559-2156143412/1956-4/19563
Cuyahoga Valley Railroad1280-128221598-2160043435/19563
Philadelphia, Bethlehem & New England392173643446/19561
Great Lakes Steel402173743325/19561
Republic Steel Corporation8952181843499/19561
Conemaugh & Black Lick120-12121831-2183243516/19562
Patapsco & Back Rivers127-12922081-2208343549/1956-10/19563
Steelton & Highspire442208443559/19561
Great Lakes Steel41-4222085-2208643561/19572
Northern Pacific1452208943587/19561
Patapsco & Back Rivers130-13422268-2227243611/1957-4/19575
Inland Steel Corporation88-8922462-22463436510/19562
Inland Steel Corporation90-9322464-2246743682/19574
Great Northern29-3322481-2248543694/1957-5/19575
Louisville & Nashville2297-230022504-2250743662/19574
Northern Pacific1462274843732/19571
Northern Pacific147-14822749-2275043792/19572
Northern Pacific149-15022751-2275243802/19572
Northern Pacific151-16222753-2276443746/1957-7/195712
Grand Trunk Western1269-127022827-2282843764/19572
Philadelphia, Bethlehem & New England40-4122903-2290443811/19572
Southern Pacific (Texas & New Orleans)123-12822906-2291143822/1957-3/19576
Aliquippa & Southern1211-121323078-2308043843/19573
Cuyahoga Valley Railroad1283-128523081-2308343853/1957-4/19573
Philadelphia, Bethlehem & New England42-4323266-2326743811/19572
Great Lakes Steel43-4423301-2330243914/19572
Baltimore & Ohio9614-962123360-2336743935/19578
Lake Superior Terminal & Transfer1052348043967/19571
Middle Electric Coal Company12012357844006/19571
Delaware, Lackawanna & Western561-56823762-2376944015/1957-6/19578
U.S. SteelSX1-SX223770-2377144028/19572
Oliver Ion Mining Company946-947946-94744048/19572
Oliver Ion Mining Company9482378544068/19571
Birmingham Southern200-20123983-2398444087/19572
Inland Steel Corporation94-9623988-2399044099/19573
Northern Pacific163-17724027-24041441012/1957-1/195815
New Orleans Public Belt71-7224063-2406444129/19572
Inland Steel Corporation97-9824090-2409144133/19582
Colorado & Southern156-16025006-2501044252/19595
Fort Worth & Denver607-61025043-2504644263/19594
Santa Fe2439-244125224-2522675736/19593
Inland Steel Corporation103-10425353-2535444287/19602
River Terminal63-6425442, 2544944295/19592
Republic Steel Corporation36225718443512/19591
De Queen & EasternD-52573144362/19601
Grand Trunk Western1511-151925743-2575144373/19609
Elgin, Joliet & Eastern300-30725847-2585444395/1960-6/19608
Inland Steel Corporation105-10625913-2591444287/19602
West Virginia Northern522603344408/19601
Chicago & North Western310-31526075-2608075937/1960-11/19606
Great Lakes Steel452615644419/19601
Great Lakes Steel4626213444310/19601
Great Lakes Steel472677944477/19611
Great Lakes Steel162713476183/19621
Chicago & North Western316-32127145-2715076202/19626
Great Lakes Steel482731244514/19621
Minneapolis, Northfield & Southern30-3127507-2750844529/19622
Reserve Mining Company121227823445312/19621
Missouri Pacific1190-119927858-2786776382/1963-3/196310
Missouri Pacific1100-112527868-2789376341/1963-4/196326
Ashley, Drew & Northern1782834444556/19631
Belt Railway Of Chicago524-52623848-2835076596/1963-7/19633
Great Lakes Steel4928676445712/19631
Missouri Pacific1126-113328747-2875476931/1964-2/19648
Missouri Pacific1179-118928755-2876577012/1964-3/196411
Missouri Pacific1175-117828766-2876977072/19644
Missouri Pacific1263-126428770-2877177024/19642
St. Louis Southwestern Railway (Cotton Belt)1062-106928895-2890276961/19648
Minneapolis, Northfield & Southern32-3328933-2893444592/19642
Inland Steel Corporation107-10828935-2893644604/19642
Commonwealth Edison162913344627/19641
Kansas City Terminal70-7929239-2924844636/1964-7/196410
Terminal Railroad Association of St Louis1227-123329440-2944677406/1964-8/19647
Great Lakes Steel50-5129483-2948444657/19642
St. Louis Southwestern Railway (Cotton Belt)1070-107329634-29637775712/1964-2/19654
Southern Pacific1597-160629638-29647446912/1964-2/196510
Minneapolis, Northfield & Southern34-3529758-2975944705/19652
Missouri Pacific1265-127429780-2978944731/1965-3/196510
Missouri Pacific1152-116629790-2980477663/1965-4/196515
Sandersville Railroad20029888447212/19641
Terminal Railroad Association of St Louis1234-124330004-3001377794/1965-5/196510
Inland Steel Corporation109-11030014-30015778012/19642
Rio Grande130-13430016-3002044751/19655
Pacific Power & Light Company103002144761/19651
Rio Grande135-13930024-3002844751/19655
Southern Pacific1607-162330239-3025544775/1965-11/196517
Peoria & Pekin Union5003030744795/19651
Inland Steel Corporation111-11430486-3048944806/19654
Cuyahoga Valley Railroad12863049044815/19651
Richmond, Fredericksburg & Potomac84-8530511-3051278117/19652
Richmond, Fredericksburg & Potomac81-8330513-3051578129/19653
Chicago, Burlington & Quincy9281-928830533-3054078046/1965-7/19658
Chicago, Burlington & Quincy9289-929230541-3054444827/1965-8/19654
Rock Island920-92830638-3064644849/1965-10/19659
Great Lakes Steel52-5330738-30739448510/19652
Rock Island929-93630743-30750448410/19658
Missouri Pacific1134-114131094-3110178493/19668
Missouri Pacific (Texas & Pacific)1280-128931110-3111944913/196610
Missouri Pacific1142-115131216-3122578593/1966-5/196610
Missouri Pacific1200-1201, 1255-1259, 1275-127931226-3123744922/1966-3/196612
Missouri Pacific (Texas & Pacific)1290-129931238-3124744913/196610
St. Louis Southwestern Railway (Cotton Belt)2289-229331570-3157478671/1966-4/19665
Houston Belt & Terminal34-3731684-3168744934/19664
Houston Belt & Terminal333168878775/19661
050283572375276737848389390878.jpgPennsylvania SW1200 #9011 (Class ES-12) was photographed here in Columbus, Ohio, circa 1966. Fred Byerly photo. American-Rails.com collection.

EMD Rebuild

(Total Built = 1)

SW1200's completed from trade-in units, reusing the same serials as their predecessors.

Owner Road Number Serial Number Order Number Completion Date Heritage Quantity
Great Northern10064775202/1955Ex-Great Northern NC #5101.1

General Motors Diesel (GMD)

(Total Built = 274)

Owner Road Number Serial Number Order Number Completion Date Quantity
Canadian National1593-1594A740-A741C1919/19552
Canadian National1595-1597A742-A744C1912/19563
Canadian National1575-1592A745-A762C1903/1956-5/195618
Canadian Forest Products301-302A830-A831C1963/19562
Canadian National1227-1247A854-A874C1985/1956-9/195621
Canadian National7020-7030A875-A885C2019/1956-10/195611
Essex Terminal105A949C2103/19561
Roberval & Saguenay Railway23A976C21211/19561
Canadian National1248-1268A1020-A1040C21511/1956-3/195721
Canadian National7031-7033A1041-A1043C2161/19573
Canadian National1271-1288A1167-A1184C2288/1957-11/195718
Canadian National1289-1304A1358-A1373C2401/1958-5/195816
Canadian Pacific8100-8130A1480-A1510C2496/1958-10/195831
Canadian National1305-1337A1542-A1574C2537/1958-12/195833
Canadian Forest Products303A1715C2594/19591
Canadian Pacific8131-8146A1731-A1746C2614/1959-5/195916
Canadian National1338-1357A1788-A1807C2645/1959-7/195920
Canadian National7034-7035A1809-A1810C2657/19592
Canadian National1358-1397A1843-A1882C2734/1960-8/196040
Canadian Pacific8147-8171A1893-A1917C2757/1960-9/196025
Quebec Iron & Titanium/Chemin de fer de la Rivière Romaine (Romaine River Railway)5A1934C2825/19611
Dominion Foundries & Steel14A2047C2956/19641

Canadian units are sometimes referred to as SW1200RS, equipped with Flexicoil trucks.


 (Total Built = 32)

Owner Road Number Serial Number Order Number Completion Date Quantity
Amapá Railway (Brazil)1-320008-20010701069-7010711/19553
Chile Exploration Company (Chile)911231197014532/19571
Chile Exploration Company (Chile)912-91323939-23940701647-7016489/19572
Chile Exploration Company (Chile)914251557020214/19591
Chile Exploration Company (Chile)915253577020227/19591
Chile Exploration Company (Chile)916-91725629-25630702267-70226811/1959-2/19602
Chile Exploration Company (Chile)918-91926652-26653700057-7000588/19612
Chile Exploration Company (Chile)920-92326769-26772700164-7001679/19614
Panama Canal Company (Panama)661-66327111-27113700390-7003926/1962-9/19623
Chile Exploration Company (Chile)924-92927456-27461700432-7004377/1962-8/19626
Chile Exploration Company (Chile)930-93528255-28260700637-7006423/19636
Amapá Railway (Brazil)4318387105875/19661


  • Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.
  • Hayden, Bob. Diesel Locomotives: Cyclopedia, Volume 2 (Model Railroader). Milwaukee: Kalmbach Publishing Company, 1980.
  • Marre, Louis A. Diesel Locomotives: The First 50 Years, A Guide To Diesels Built Before 1972.  Milwaukee: Kalmbach Publishing Company, 1995.
  • Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.
  • Solomon, Brian.  EMD Locomotives.  Minneapolis: MBI Publishing Company, 2006.

92835273527357828963948983798459.jpgMilwaukee Road SW1200 #601 carries out switching chores at what appears to be the Bensenville, Illinois terminal on May 15, 1971. Photographer unknown. American-Rails.com collection.

Unfortunately, this 8-cylinder variant's slightly longer frame and higher cab caused clearance issues for private industries.  As a result, EMD would release an updated version, the SW1001, to correct these flaws.

The SW1200's immediate successor was the 12-cylinder SW1500, a model that continued the success of its predecessor and saw more than 800 units produced at La Grange.  Today's the powerful and versatile SW1200 is still quite common in industrial settings.


Wes Barris's SteamLocomotive.com is simply the best web resource on the study of steam locomotives. 

It is difficult to truly articulate just how much material can be found at this website. 

It is quite staggering and a must visit!