Aggregate economic activity was heavily influenced by the construction sector's expansion, collapse, and failure to revive during the interwar years. The 1920s building boom was the first to respond to the potential of the automobile and the last to be largely unplanned. Its uncoordinated character slowed the growth of full employment output toward the end of the 1920s. The physical and legal detritus of unregulated land development posed continuing obstacles to recovery during the second half of the 1930s.