What HO means
HO stands for “half O,” since the scale is about half the size of O scale. The ratio is about 1:87 (the NMRA gives 1:87.1), and the track gauge is 16.5 mm. Some sources link the name to the German Halb-null, or “half zero.” The name stuck even though the “O” was originally a number-style label, not a letter.
Early European roots
Smaller table-top trains began appearing in Europe in the 1920s as an alternative to the larger scales used for toy trains. Sources commonly mention the German maker Bing, which sold a small table railway in the 1920s. Märklin showed an electric 00-gauge system at the Leipzig fair in 1935, using 16.5 mm track, and that track width became the basis of HO. Other European firms soon joined in.
The Great Depression and shrinking living spaces are often cited as reasons smaller trains made sense, though exact causes are hard to pin down.
Postwar growth in America
After World War II, interest in a more realistic hobby grew. Smaller models meant that a decent layout could fit in a spare room or on a sheet of plywood. American companies such as Athearn (which dates back to the late 1930s) and Mantua made locomotives and rolling stock, and kits let hobbyists build their own fleets. In Britain, the OO variant (1:76.2 on the same 16.5 mm track) became dominant, which is why British and North American modelers use similar track but different scale ratios. For the numbers behind that, see model train scale sizes explained.
Brass and plastic
During the 1950s and later, imported brass locomotives, often from Japan, offered detailed models for collectors and serious modelers at a high price. Meanwhile, injection-molded plastic made affordable, repeatable models possible. Plastic locomotives and cars, along with reliable power packs, brought the hobby to many more people.
Ready-to-run decline and revival
By the 1960s and 1970s, makers such as Tyco, Athearn and others sold inexpensive ready-to-run trains and starter sets. Many accounts describe a downturn in the hobby in later decades, followed by a revival as manufacturers invested in finer detail, better running and more accurate paint. Today a wide range of ready-to-run models, kits and parts exist, from budget sets to very detailed models.
DCC and sound
Digital Command Control (DCC) began to spread in the late 1980s and 1990s and was later standardized by the NMRA. It let modelers run several trains independently on the same track and led to sound-equipped locomotives. Many HO locomotives now come “DCC-ready” or with sound. If you are new to this, see the overview in model train types and brands.
Why HO took over
Common reasons given include:
- A workable balance of size and detail.
- A large range of products and used equipment.
- A big base of hobbyists, which supports the whole industry.
- Standards that let different makers’ products work together.
N scale and others grew too, but HO stayed the one with the widest choice, especially in North America.
Did Lionel ever make HO scale trains?
Yes. Lionel, best known for O gauge toy trains, sold an HO line for a period starting in the late 1950s, and the brand has appeared on other HO products at various times. The details of each era differ, so check a collector guide for specifics.
Are old HO scale trains worth anything?
Sometimes. Value depends on the maker, rarity, condition, completeness and whether the original box is present. Many common starter-set items from the 1960s and 1970s are inexpensive, while certain brass models and uncommon items can bring more. Check recent sold listings and collector references instead of relying on asking prices.
How to tell how old a model train is
- Markings: Look at the underside and the frame for maker names, model numbers and dates.
- Packaging: Box styles and printed catalog numbers often point to an era.
- Construction: Materials, wheels, couplers and motors changed over time.
- Catalogs and collector guides: Matching your item to a catalog is often the most reliable method.
If the piece is valuable to you, a collector club can help.
Who makes the highest quality HO scale trains?
Quality depends on the era and the product line, and opinions differ. Hobbyists often name Kato, Rapido, Athearn’s premium lines, Atlas, Walthers’ premium lines, Broadway Limited Imports, ScaleTrains and European makers such as Märklin and Roco for various models. Read recent reviews for the exact locomotive you are considering.