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.

Best of the Web (“Hall of Fame”)



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

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]

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

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Recent News: HO Scale Model Trains

Source: Google News

Executive Q&A: Scott O'Donnell says Circus World is more of an attraction now
Madison.com, April 20th

We also have some amazing miniature models that are going on display here, including an HO-scale replica of the 1947 Ringling Bros. and Barnum & Bailey Circus train. It's 35 feet long. Q: Why are you bringing a tent back for the circus performances?...Read more

Pasadena Model Railroad Club Spring 2014 Open House
Alhambra Source, April 18th

A model train show for all ages. The club operates the Sierra Pacific Lines one of the largest HO scale-operating model railroads in the world covering almost 5,000 square feet. Trains from all eras are operated, steam, diesel, modern freight, old...Read more

Times Staff Report
Gadsden Times, April 18th

Kids of all ages who enjoy watching model trains run will have plenty of opportunities Saturday when the Coosa Valley Model Railroad Association hosts its 28th annual Train Show at Convention Hall. Association President Jim Bertch said five operating...Read more

Annual train show to be held Saturday at Convention Hall
Gadsden Times, April 15th

In addition, the $5 admission price — children under 12 get in free — will include admission Saturday to the Hardin Center, home of the 26-foot by 72-foot, HO scale Coosa Valley Model Railroad. It's the largest site/date-specific layout east of the...Read more

Third Annual Jefferson Train Days
Gilmer Mirror, April 11th

The late R.D. Moses and his late friend, Jack Luck, spent over 30 years creating and building this fabulous HO scale model railroad layout that depicted the Texas & Pacific Railway in West Texas in the 1950s.This superb model railroad was published in...Read more

Lake County Model Railroad Club's track layout in Wauconda is an ever ...
Libertyville Review, April 6th

There's a “wow” factor about the Lake County Model Railroad Club in Wauconda. “The moment they walk through the door, a lot of visitors say 'Wow!'” said Norm Kocol of Johnsburg, a member of the club since 1976. “They can't believe it.” The club...Read more

Ligonier Valley model train home tour on track for May 3
Tribune-Review, April 2nd

Dick Flock will provide a walk-through HO-scale display that he operates like a real railroad at the basement of his Greensburg home. Flock, 78, presented an “L-shaped” layout during the first tour. Since that time he has added several new features...Read more

Model train builders donate hours of work to create detailed display for ...
The Republic, March 31st

Thanks to a monetary gift from a local family and a gift of time and knowledge from a group of volunteers, park visitors will be able to congregate outside a scaled-down version of a train depot, where they can watch an even smaller scale HO model...Read more