HO scale model trains are 1/87 the size of real trains and 1/2 the size of O scale model trains (HO stands for "half O"). As with O scale trains, the letter "O" in HO is a misnomer since the designation was initially conceived as a zero to identify trains that were smaller in scale than 1. But the use of the letter O rather than the numeral 0 crept into everyday speech among model-train buffs and remains the standard way to refer to HO scale today.

Though first invented in the 1930s, HO scale model trains didn’t become popular in the U.S. and Europe until the 1950s when the scale was heavily promoted by Märklin, Lionel, Athearn, and others. HO never quite gained acceptance in England, though, where larger 00 scale trains still predominate.

HO has two important benefits over trains of larger sizes. First, an HO scale layout of reasonably ambitious detail and complexity can fit on a table rather than requiring an entire room, as is the case with larger scales. Second, HO trains are less expensive to manufacture than OO, O, and other large-scale trains, which makes them more affordable to collectors and enthusiasts alike.

Most HO scale trains run on two-rail tracks using direct current (DC). Adjusting the voltage delivered to the tracks can increase or decrease the speed of the trains; reversing the polarity causes the trains to roll in reverse. Some manufacturers, notably Märklin, produce HO scale trains that operate on alternating current (AC), which is delivered to the train via a conductive third rail.

The gauge used by the majority of HO scale model trains is a standard HO gauge track that’s roughly proportional to the size of the trains running on top of it. But as with the OO scale trains in England that run on HO gauge tracks, HO scale trains are also made to run on a variety of different gauge tracks, which themselves are scaled-down versions of historical railroad track sizes.

Of these variants, the most common is called HOn3. This code denotes an HO scale train running on a track similar to the 3-foot, narrow gauge tracks used by Rocky Mountain railroad operators in the late 19th century.

One of the most enjoyable aspects of HO for collectors is the opportunity to join a local module club. Members of such clubs build modules of predetermined size; each module has a finite length of track. When members get together at model train exhibitions or in private homes, the modules are linked up and trains are run on the resulting massive layout, which often feels like more than just the sum of its parts.

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

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

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Postwar Lionel Trains Library

Postwar Lionel Trains Library

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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

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Recent News: HO Scale Model Trains

Source: Google News

Model Railroad display
KKTV 11 News, April 18th

The Pikemasters model railroad club is hosting our annual Spring Open house. We will be displaying our large permanent HO scale (1:87th) layout in the basement of the city auditorium to the public. On hand will be the Colorado and Southern Historical ...Read more

Full steam ahead
Brownwood Bulletin, April 17th

Jim Howell, a member of the Lehnis Heart of Texas Model Railroad Club, places an HO scale model railroad car on the track Friday afternoon at the Depot Cultural Center in preparation of this weekend's Heart of Texas Railroad Festival. ... and the...Read more

Community Notes: April 17, 2015
Daily Astorian, April 16th

Angora Hiking Club — 10 a.m., Pacific Way Bakery, 601 Pacific Way, Gearhart. Gearhart Nosh. For information, call Kit Ketcham at 503-717-5027. Columbia Northwestern Model Railroading Club — 1 p.m., in Hammond. Group runs trains on HO-scale layout...Read more

Must See Must Do: What's happening around Colorado Springs this weekend
Colorado Springs Gazette, April 16th

The trains are running, this time in the City Auditorium, 221 E. Kiowa St., for this weekend's annual April open house of Pikemasters Model Railroad Club. From 10 a.m. to 4 p.m. Saturday and Sunday, the HO scale layout will be a busy page from...Read more

Miniatures in motion
North Platte Telegraph, April 16th

Gene Tacey's HO Scale model railroad is set in the 1950s. To keep with the setting, some of his train cars were ready-made and then customized, others were completely hand painted. Pictured is his main train yard. Tacey's entire setup is 20 feet by 12...Read more

Annual model train show Saturday
Gadsden Times, April 11th

railroad memorabilia, in addition to model trains. There also will be a hot food and snack bar, and door prizes will be awarded. Admission is $5; children younger than 12 get in free. It includes admission Saturday to the Hardin Center, where the...Read more

Model Train Show at the Fairfax Station Railroad Museum
Virginia Connection Newspapers, April 8th

The Potomac Module Crew (PMC) members will have a two day HO scale modular train display running at the Fairfax Station Railroad Museum on Saturday May 2, from noon to 5 p.m. and Sunday, May 3, from noon to 4 p.m. They will be joined by a custom ...Read more

Booted From Union Station, Model Railroad Club Back on Track to Fund New ...
Westword, April 3rd

When the trains pulled back into the renovated Union Station last year, one stop was conspicuous by its absence: the model train layouts that had graced the basement of the building for decades, and were featured at regular open houses for the public...Read more