O gauge refers to model train tracks whose rails are 1¼ inches apart. Even though O scale model trains frequently run on O gauge tracks, strictly speaking, the two Os have nothing to do with each other.

The letter "O" is actually a misnomer since the designation was initially conceived to identify trains and tracks that were smaller in size than 1, which had been the standard. Since the only number smaller than 1 is 0, that’s how early O scale trains and O gauge tracks were identified, but the letter O (pronounced “owe”) crept into everyday use among model train buffs and has remained the way to refer to the gauge ever since.

The O gauge was introduced to allow toy manufacturers to sell trains that took up less space than their standard counterparts. These trains were also less expensive for customers. At one point or another, Märklin, Lionel, American Flyer, Dorfan, and Ives all made models trains designed to run on O gauge tracks.

This smaller size took off in the 1930s, when affordability trumped most other concerns thanks to the Depression. It was adopted wholeheartedly by Lionel, which sold two different O gauges for its O scale toy trains. Lionel’s regular O gauge track was the same width as its O-27 gauge track (1 ¼ inch), but the O-27 had a lower profile than regular O, and its thinner rails allowed all but the longest O scale model trains to make tighter turns (a circle of O-27 tracks has a diameter of 27 inches instead of 31).

Some of the most famous and sought-after model trains ran on O gauge tracks. Cars with vista domes for Santa Fe, B&O, and New York Central lines, among others, are considered standards of any self-respecting O gauge collection, even if the car was an East Coast line (tunnels back east were too low for vista domes, so in reality they only ran out west). Pointed observation cars such as the ones for the Empire State Express are also popular, as is a short N5 caboose labeled Pennsylvania or Lehigh Valley.

Other model trains sought by O gauge collectors include a work caboose with a boom tender, a Fairbanks-More Trainmaster locomotive (it was painted orange and blue, even though those colors never appeared in real life), and steam locomotives such as Lionel’s S2 Turbine. After World War II, Lionel actually made four versions of the S2 locomotive in both O and O-27 gauges.


Best of the Web (“Hall of Fame”)

Airfix Model Railways

Airfix Model Railways

Dave McCarthy's Airfix Model Railway treasure trove is an in-depth archive of the company's plastic railway kits fr… [read review or visit site]

Gateway NMRA

Gateway NMRA

This great reference site for model railroaders, from the Gateway (St. Louis) division of the NMRA (National Model … [read review or visit site]

HOseeker.net

HOseeker.net

This site is a treasure trove of HO scale model railroad manufacturer catalogs and other reference information, inv… [read review or visit site]

Postwar Lionel Trains Library

Postwar Lionel Trains Library

Bernie Schulz’s Lionel Trains Library focuses exclusively on postwar Lionel trains and accessories. The site cont… [read review or visit site]

Eric's Trains

Eric's Trains

Eric Siegel's site displays his collection of O-gauge/O-scale trains, tracks, turntables, and other accessories. A … [read review or visit site]

Tech Model Railroad Club of MIT

Tech Model Railroad Club of MIT

MIT's model railroad club, as one might expect, has one of the best websites for learning about how people play wit… [read review or visit site]



Clubs & Associations

Discussion Forums

Other Great Reference Sites

Most watched eBay auctions    

Early Live Steam Locomotive Weeden ??? Great Condition O Gauge Circa Late 20sHornby O Gauge - Nos 2 Special Lms Compound 1185 Locomotive & Tender -boxedModel O Gauge Brass EngineHornby O Gauge 31801 4-4-2 Clockwork 3c Locomotive & Tender -r/viera (nord)637 Loco 736w Pennsylvania Whistle Tender Clean Lionel Postwar 0 Gauge D660Lionel # 2671w Pennsylvania Tender W/ Whistle * O GaugeLionel Trains Post-war No.2026 2-6-2 Steam Locomotive & Tender, O GaugeLionel Std. Gauge # 10e Electric Engine + 332 339 341 Passenger Cars(dakotapaul)Lionel 263e Locomotive "o" Gauge Blue Comet ? Pre-war ? No ReserveHornby O Gauge 1932 4-4-2 T E220 20 Volt 3 Rail GwrO Gauge -k-line Nyc Empire State Express Steam Engine & Tender Cab # 5426 Gb Es1950's Unique Art Lithographed Tinplate O Gauge Scale 7.5"l Cattle Train Car6500 Beechcraft Bonanza Transport Car Flat Original Lionel Postwar 0 Gauge D659 Lionel O Gauge Train 736 Berkshire 2-8-4 Steam Locomotive & Tender W/ CarsLionel 0/027 Gauge Penn F3a Dual Motor Diesel #6-8970-71Lionel-nice O-gauge 665 Hudson-4-6-4-l@@k!!!Lobaugh Brass 'o' Gauge Heinz Pickle Tank Car KitMth Railking Amtrak F59 Diesel Loco Sounds O-gauge #456Lionel Trains Postwar No. 41 O Gauge United States Army Diesel Switcher EngineElektro-keiser Re 4/4 Locomotive For Elettren Or Herman Cars O-gauge 3-rail DcLionel O Gauge Mpc Freight Cars (19)/boxMth O Gauge Esso Operating Gas Station 1965 Mustang 30-9106 Excellent ConditionIves "o" Gauge 131 Tin Lithographed Baggage Car, Circa 1910, All Original-nice!Lionel O Gauge Postwar Freight Cars (7)January 1989 Overland Ajin Brass O-gauge 2-rail Dash 8 LocomotiveLionel Train No. 262e O Gauge Locomotive With Original BoxLionel O Gauge 675 Engine W/ 2466wx, 2443, 2442 (2) Cars 5pc As Shown Prewar Lionel Standard Gauge No.380 Electric EngineK-line K2436-2002 Metrolink F59phi Railsounds-tmcc Equipped O-gauge Lionel Pre-war O Gauge #252 Electric Train Engine1/4 Inch Scale, On2 Gauge, Brass Locomotive Sandy River & Rangeley Lakes No. 16Lionel 2056 Locomotive Steam Engine In Box 027 GaugeIves O Gauge No.5 Windup Locomotive No.1 Tender No.50 Baggage & Lionel 801 Cabo Huge Lot Atlas O Gauge 2 Rail Track 42 Curve 47 Straight Right & Left SwitchVtg~williams Trainmaster~2381 Santa Fe~diesel Locomotive~o Gauge~new & Unused~Original Prewar Lionel Flying Yankee Streamline Train O GaugeLionel O Gauge Prewar 260 Loco W/ 263w Tender ProjectLionel O Gauge O-54 Curved Track - Excellent ConditionLionel O Gauge No.6-18023 Western Maryland Shay Steam Engine With BoxLionel Trains Postwar No.2025 Steam Locomotive W/6466w Tender, O GaugeLionel O Gauge 40 Inch Track - 11 Pieces - Used - Excellent Condition Lionel Prewar O Gauge 248 Electric Locomotive Lionel O Gauge 6-8951 Southern Pacific Train Master Fairbanks Morse W/ BoxDorfan O Gauge 8-wheel 610 Crane Or Derrick CarVintage Lionel Gg-1 Penn Central 8850 O & 027 Gauge Engine Clean In Box Sakai Seki Tokyo Japan Prewar O Gauge Tinplate Center Door Passenger Car 47029House Of Duddy 010 Brass O Gauge 70 Ft. High Tension Anchor TowerLionel O Gauge F-3 Santa Fe Engine 6-18117 8100 2 Motor EngineLionel152 Electric Loco Early Dk Green Prewar O Gauge Serviced Cleaned Runs GoodMth Train O Gauge Premier Pennsylvania N-6b Caboose 20-91123 MibLionel O Gauge # 746 Norfolk & Western 4-8-4 Steam Loco, # 746w Tender & BoxesVintage Prewar Ives Railway Lines No. 3252 Electric Locomotive - Green - O GaugeK-line Canadiam Pacific Aluminum 15" Passenger Cars 2-pac K-4618c O-gaugeK-line Canadiam Pacific Aluminum 15" Passenger Cars 2-pac K-4618a O-gaugeLionel O Gauge Postwar No. 2530 Aluminum Rea Baggage CarShorty's General Store Custom Made O-gauge Wooden BuildingLionel #18745 Halloween Hallow's Eve Steam Locomotive Engine 4-6-0 Train O GaugeLionel O Gauge Train Engine #726Scarce Jep O Gauge 2b2 5272l Electric LocomotiveMth 30-74310 New York Giants Boxcar O Gauge Train Car Nfl Football Ny Railking