Who benefits more? The heterogeneous impact of highways on employment growth

This paper explores the relationship between the stock of interstate highways on employment growth of counties in Texas between 1983 and 2012. Using the Chernozhukov-Hansen instrumental variables quantile regression (IVQR) method, we examine the heterogeneous impact that highways have on employment growth at different quantiles of the conditional distribution while at the same time controlling for potential endogeneity. The results show that the employment growth effect monotonically increases as one shifts from the lower tail to the upper tail of the distribution. The range is 0.15 to 0.44, with the highest at the 95th quantile, compared to 0.189 for OLS and 0.213 for 2SLS. A 10 percent increase in interstate highway kilometers in 1983 led to about a 1.5 to 4.4 percentage point increase in county employment over a 29-year period. Our results also indicate that the counties with low initial levels of employment grew faster than those with a high initial level of employment and that this convergence monotonically decreases from the lower tail to the upper tail of the growth distribution.