type of residential building, characteristically built on one level, having a low roof and a rectangular open plan, with relatively little conventional demarcation of living areas.

When the settlers of the western United States abandoned their original log cabins, sod houses, and dugouts, they built small, wood-framed dwellings of one or two rooms without a basement; rooms were usually added as the family or settlers grew more numerous and more prosperous. This usually resulted in a series of large, open rooms laid end to end so that each would have an equal amount of sunlight, open to, and closely allied with, the surrounding terrain. From these old ranch houses of the western United States, a new type of American home developed during the 1920s, sometimes called the in-line house, built on what is known as the long plan. During the building boom after World War II, the style was particularly popular.