Multiple similar homes built closely together on parcels of land subdivided into individual lots characterize the architectural concept of tract housing. Many early tract housing developments in the United States featured identical homes, but modern developments incorporate a variety of architectural designs. Tract homes often offer good value to consumers because building costs are less than having a home custom built as many tract homes are built simultaneously, substantially reducing material and labor costs. Some components of tract housing, such as stairs and roof trusses, are prefabricated, which allows developers to pass on savings to home buyers. Tract housing in the United States originated from Europe's row housing developments. The first significant tract housing development in the U.S, was at Leviton, New York, when entire suburbs were mass produced to accommodate young families after the end of the second World War.