From the early 20th century up to the 1940s houses were designed with a narrow street façade and a plan that went deep into the property, but by the 1940s a transition began to occur. Primarily because of wartime economics, the narrow, deep floor plan of the bungalow and period cottage types transformed to a single-story, square, boxy plan with small rooms situated around a core. This plan economized space and allowed for easily mass-producible housing at a time when resources and manpower were scarce. The earlier period cottage types transitioned in the 1940s as the appearance became less vertical and more boxy and compact. Gables are not as steeply pitched and the overall appearance is simpler. The enclosed, attached garage became a major feature with this house type as the automobile flourished following the war. Attached garages are typically small and found on the side of the house. As demand for housing reached all time highs following the war, the World War II era cottage was constructed in vast numbers in large, concentrated suburban tracts across the country, most notably in the Levittown developments in the Northeastern United States.