"Both human capital and nonhuman capital play an important role in economic growth. Estimates of nonhuman (physical) capital exist for many more countries than for human capital. Recently there has been a significant increase in the number of countries for which estimates of human capital exist,...

This paper constructs updated measures of productive highway capital stocks at the total, Interstate, Non-interstate, and Local System levels to estimate the contribution of all highways (all public roads) to GDP growth. It presents three types of contribution to GDP growth estimates and an...