Did Highways Cause Suburbanization?
利用美国州际高速公路系统规划路段的外生变化，估计一条穿过中心城市的新高速公路使其人口减少约18%，并反事实推断若无该系统，中心城市人口将增长约8%。
Between 1950 and 1990, the aggregate population of central cities in the United States declined by 17 percent despite population growth of 72 percent in metropolitan areas as a whole. This paper assesses the extent to which the construction of new limited access highways has contributed to central city population decline. Using planned portions of the interstate highway system as a source of exogenous variation, empirical estimates indicate that one new highway passing through a central city reduces its population by about 18 percent. Estimates imply that aggregate central city population would have grown by about 8 percent had the interstate highway system not been built.