A cross-sectional analysis of 113 countries in 1968 indicates that population density has a significant and strong effect on total road density. An elasticity of 0.73 of road density with respect to population density was obtained. Time-series analysis confirmed this finding. An elasticity higher than unity was obtained for paved road construction. The effect on unpaved roads was somewhat smaller (0.6 elasticity) but still significant. These results suggest that population increases produce more available infrastructure/worker. The effects of both population density and per capita income on road construction are influenced by the stage of economic development. When the sample was divided into 3 income subsamples increased population density and per capita income were found to cause the substitution of paved for unpaved roads in the richer countries. At lower levels of income per capita income is less important than population density in influencing road construction since village volunteer labor can be substituted for money expenditures.