Since information on U. S. household expenditures was first collected, transport expenditures have risen from the sixth-highest share of household budgets, less than 2%, in 1917 to the second-highest share since the 1970s. This rise is linked to increased automobile purchase and automobile use and a relative decline in other costs, particularly food. Studies have also linked variations in the built environment to transport expenditures, but this influence cannot be tested by the federal Consumer Expenditure Survey since it is reported at the metropolitan level. Regional travel demand models recognize the dual influence of land use and household characteristics but do not include sufficient detail on the built environment of neighborhoods. Published in Transportation Research Record: Journal of the Transportation Research Board.