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The Early Design Evolution of the American Travel Trailer

The ten key steps in American travel trailer design.

An early horse buggy towing a luggage trailer, demonstrating how trailers pre-date the automobile era (USA date unknown, source Popular Science Monthly November 1921, courtesy, original at:


Recent discoveries of early twentieth century American camping trailers have allowed us to fill in some gaps in the early design evolution of the travel trailer. The travel trailer in all its forms is still the dominant form of American RV today. The 'housecar' or motorhome followed a different evolutionary path and will be explored in a future blog.

These recent discoveries help us to understand that the travel trailer as towed by an automobile evolved from horse-drawn vehicles. This is not surprising, since all wagons drawn by beasts of burden are, after all, forms of trailers. Four of the ten steps below took place in the horse-drawn era, emphasizing how important it is to consider this period in the history of the RV.

In between the ten major design steps below are many half-steps. These involved the use of different materials and variations in shape, size and facilities.

Step One: The Ambulance Wagon (1850-1880)

The Wheeling or Rosencrans ambulance wagon (USA, 1860s)

The ambulance wagon was used outside wartime during the nineteenth century by westward-headed health seekers as they sought a better climate to help cure consumption. It is a design predecessor to the travel trailer because it had a flat floor, high ground clearance, soft springs and was partially enclosed by solid boards. It was the first form of horse-drawn transport in America designed to carry people lying down in modest comfort.

Further details on the ambulance wagon can be found in the blog Health Before Recreation.

Step Two: The Hunting or Camping Wagon (1880-1910)

An early twentieth century camping wagon (USA, source Pearson's magazine July 1905)

The hunting or camping wagon expanded the principles of the ambulance wagon by offering dedicated accommodation for hunters or early tourists. Beds were basic affairs, either on a raised wooden platform inside the wagon with underbed storage or canvas attached to slide-out gas pipes. The mess or cooking area was usually a fold-down board at the rear revealing food storage areas and a portable kerosene cooker. Tents would often be brought along for extra sleeping or bathroom facilities. Two or three horses were needed for these heavier wagons. Most were built by coachbuilders and hired out to clients for short camping trips.

Step Three: The 'House on Wheels' (1885-1914)

Various 'house on wheels' designs in use from 1896-99 (source Library of Congress)

"House on wheels' was the generic term given by newspaper journalists to horse-drawn vehicles containing accommodation. They were all either self-built or one-offs made by a coach builder to the order of a client. They varied significantly in size, materials and quality depending on budget and purpose, but most used the basic box shape of the ambulance and camping wagons. Attempts were made to provide better sleeping accommodation and to make these vehicles more 'homely' than camping wagons, often with female design input. Some travelers crossed the continent in this type of wagon.

Further details on some houses on wheels can be found in the blog American Houses on Wheels.

Step Four: The Camping Car (1889)

The McMaster Camping Car (1889, source US National Parks Service)

The McMaster Camping Car is America's first-known, purpose-built RV, patented in 1889. A handful of these camping cars were built for Alonzo McMaster himself and a small number of clients. Two were built for hire by tourists in Yellowstone National Park in 1892.

The McMaster Camping Car contained a number of advances over camping wagons and 'houses on wheels' such as a sliding oil stove that could be brought inside the car to provide warmth, benches that could be converted into beds and even a ladder strung under the car that was used as a cot for the driver. It was the first real 'travel trailer' pulled by horses.

Further details on the McMaster Camping Car can be found in the blog America's First RV.

Step Five: The Automobile Trailer (1906)

The Stewart Auto Camp Wagon (USA 1906, source Los Angeles Times 8 Sep 1906 from

The arrival of the automobile meant that trailers needed (for a time) to become smaller. The low-powered engines of the first automobiles could tow only lightweight trailers, so the horse to horsepower transition saw a step down in camping trailer size and facilities.

The 1906 Auto Camp Wagon of Los Angeles car dealer Alfred C. Stewart is significant because it helps us to bridge the design gap between horse-drawn camping wagons of the late 1890s and the automobile camping trailers of the mid 1910s. Although it was not much more than a storage cart on four wheels, Stewart showed that such a configuration was a viable alternative to 'auto camping' (putting camping equipment inside or attached to an automobile) for a camping expedition over several hundred miles. Fears of damage to the automobile from towing stress or punitive fuel consumption proved unfounded.

Further details on the Stewart Auto Camp Wagon can be found here.

Step Six: The Early Camping Trailer (1910)

The Sterling automobile and camping trailer of Dr. Charles A. Morsman (source Joplin News Herald, 29 Jan 1911)

Dr. Morsman's camping trailer is different to the Stewart Auto Camp Wagon because Dr. Morsman's trailer was purpose-built for camping. It began a two-step process in the design of camping trailers that moved from storing camping equipment in a purpose-built trailer to incorporating tent accommodation as part of the trailer. It's important because it predates commercial, purpose-built camping trailers by at least three years.

Further details on the Morsman Automobile Camping Trailer can be found here.

Step Seven: The Advanced Camping Trailer (1915-30)

The Warner Auto Trailer (USA 1916, courtesy Joel Silvey)

More advanced camping trailers came along after 1915, with the advent of the 'pop-up' camper trailer. A tent attached to the trailer would lift upwards and outwards, allowing the trailer base to become a bed. Storage and cooking facilities were built into these trailers. Since camping in the 1920s was largely confined to shorter trips during warmer weather, there was no need (yet) for a fully enclosed trailer.

Further details on the history of the camping trailer can be found at

Step Eight: The Fifth Wheeler (1928)

The Curtiss Aerocar of Roy D. Chapin (USA 1930s, courtesy Glenn H. Curtiss Museum)

Glenn H. Curtiss' RVs are important, not just because they were mainly fifth wheelers, but also because they were fully enclosed. During the late 1920s many people grew tired of camping under canvas and wanted more comfort and protection. The refusal of wives of avid campers to 'rough it' in a tent was the catalyst for the birth of a number of travel trailer firms.

The fifth wheel trailer concept was first used by Curtiss in a prototype for the Adams Motorbungalo in about 1920, but the 1928 version using Curtiss' patented Aero Coupler was a masterstroke of engineering. It brought stability at speed to larger trailers. By being full enclosed, canvas was a thing of the past and all-year-round (and family) RV use could be contemplated for the first time.

The fifth wheeler is a major design branch of the travel trailer and remains highly popular today thanks to Curtiss' innovation of 1928.

Further details on the Curtiss Autocar can be found in the blog The RVs of Glenn H. Curtiss.

Step Nine: The 'Canned Ham' Travel Trailer (1930 onwards)

The Schult Sportsman (USA 1936, courtesy Al Hesselbart)

Call them 'jelly beans', 'canned hams' or 'mushroom' trailers, the full-height aerodynamic look for trailers arrived in about 1930. As automobiles became faster, roads better and journeys longer, trailer drag was thought to increase fuel consumption. So when sheet metal for automobile manufacturing could be stamped out cheaply using curved panels, the idea was carried over into travel trailers using timber or bondwood. It's possible that the canned ham trailers were based on rounded caravan designs seen in the UK, where manufacturers had realised that a caravan did not need to be full height along its entire length.

Before long 'canned hams' appeared in all shapes and sizes, including the diminutive teardrop trailer which was first seen in Los Angeles in about 1936.

With apologies to Airstream and Bowlus fans, shiny Duralumin trailers are, for the purposes of this blog viewed as a sub-group of the canned ham trailer. Far more beautiful, admittedly, but still aerodynamic cans on wheels.

Step Ten: The 'Toaster' (1930 onwards)

The Bender Body Company Trailer (USA 1936-7, source Detroit Public Library)

'Toasters' came about at the same time as or shortly after the canned ham trailer. They were developed for two main reasons. Firstly, the toaster shape could hold more appliances than the canned ham trailer, which was an important requirement when entire families were traveling together, or trailers were being lived in full-time. Secondly, during the Great Depression, trailer manufacturers needed to diversify sales away from families towards businesses and traveling salesmen. The toaster was a more flexible design for business use, allowing more space for mobile offices, displays and commercial storage. As a result the toaster had a broader customer base than the canned ham.

Modern travel trailers are often hybrids of these last two design groups, combining the practical advantages of the toaster with the aerodynamics of the canned ham.


The early design evolution of the travel trailer demonstrates not only how old this form of travel is, but also how adaptable it has been to changes in propulsion, road conditions, technology advances and consumer demands.

Thanks to the digital archiving of old newspapers and images, we are now beginning to see the whole story of RV design history for the first time.

The design evolution of the American 'housecar' or motorhome will feature in a separate blog in 2023.

Andrew Woodmansey

December 2022


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