In the U.S., the modern Recreational Vehicle RV industry had its beginnings in the late 1920s and 1930s shortly after the advent of the automobile industry, where a number of companies began manufacturing house trailers or trailer coaches, as they were then called. Often, these started out as mom and pop operations, building their units in garages or back yards. One of these early manufacturers, Airstream, is still in business today.Though tied to the mobile home industry in the early years—when few units were longer than 9 metres (30 ft) long, and thus easily transportable—the 1950s saw a separation of the two, as what are now referred to as mobile homes became larger and more immobile, and thus largely became an entirely separate industry. During the 1950s, in addition to travel trailers or trailer coaches, manufacturers began building self-contained motorhomes.