The impact of interstate highways on land use conversion

Between 1945 and 2007, the United States lost 19.3 % of its agricultural land. Over the same time period, the construction of the 42,500 mile interstate highway system lowered transportation costs and opened large tracts of land for development. This paper assesses the impact of the interstate highway system on agricultural land loss in Georgia and uses the empirical estimates to simulate agricultural land loss resulting from the construction of additional interstate highways. Using a historical data set of agricultural land and interstate highway mileage, empirical estimates indicate that each additional mile of interstate highway reduces agricultural land by 468 acres. The impact of interstate highways is heterogeneous across initial level of county development. Urban counties convert 70 % more land than the full sample estimates. Simulation results show that additions to the interstate system create further loss of agricultural land. The results imply that future conservation programs need to consider how to mitigate the impact of the interstate highway system.