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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Airfix Model Railways

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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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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

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Recent News: HO Scale Model Trains

Source: Google News

“This is such a fun, all-generations day:” Mitchell Park Domes hosts model ...
fox6now.com, January 31st

The event features masters of train layouts who fill the lobby with their displays, from the tiniest Z-scale trains to the most popular HO-scale and larger models. “This is such a fun, all-generations day. It's such a hoot to see young boys and girls...Read more

EnterTRAINment Junction celebrates 'Everything Thomas'
Hamilton Journal News (subscription), January 27th

The event includes several Thomas wooden train layouts, Thomas HO scale electric train display, videos, Thomas & Friends scavenger hunts and crafts, and a hobby & toy shop with the area's largest selection of Thomas merchandise from 15 to 50 percent...Read more

Are model trains still relevant? Hobbyists stay on track at the Great Train ...
OregonLive.com, January 24th

Matthew Wilson and Josh Johanson aren't really sure why they like trains so much. The two friends, 21 and 22 years old respectively, controlled small HO-scale trains as they searched for the answer. "I don't know, something about the power of it...Read more

Model train show returns for two-day run in Albany | VIDEO
The Albany Herald, January 20th

There are spurs, sidetracks and up to three tracks running side by side on some parts of the layout, and the system is interconnected so that trains can be switched from one track to another. ##“We have a layout that's got over 400 feet of HO (scale...Read more

Amherst Train Show Pulling Into Eastern States Expo
Hartford Courant, January 20th

Thousands of model train enthusiasts from across the country and Canada will converge on the Eastern States Exposition grounds in West Springfield for the annual Amherst Railway Society Railroad Hobby Show on Saturday and Sunday, Jan 24 and 25...Read more

Model train show at Campbell River Museum
Comox Valley Echo, January 20th

Operating HO Scale trains and Garden Scale trains from the North Island Model Railroaders will be on display. Incredible arrangements of equipment, scenery and miniature buildings will all be available for 'looking and learning'. According to member...Read more

Shorewood Hills model train layout goes all the way to Dubuque
Harborcountry News, January 7th

“I have a whole train of cars and I have to determine the best way in the least number of moves possible to drop and pickup all my cars, because every move costs the railroad money in real life,” he said. “It's a video game in 3-D is what it boils down...Read more

Patcong Valley Model Railroad Club 30th Annual Open House Train Show
The Ocean Signal, January 4th

Come to see highly detailed HO scale models of many different trains, operated on a large realistic model railroad thru beautiful scale scenery of Western PA and Eastern NY State. This is a coal country bridge route. We operate 6 to 8 trains at a time...Read more