Abstract This paper examines theoretically and empirically the effects of public investmentrules on output growth in an economy with private and public capital. It is shownthat the decisions on public capital formation are closely associated with the growthrate of output and generate endogenous growth. A permanent change in the policyrule implies a new long‐run growth rate of output, but the economy will onlygradually approach the new steady‐state due to adjustment costs in private capitalaccumulation. The model predictions are tested using data from Canada for theperiod 1955‐1999. The data support the endogenous growth hypothesis and thetwo central assumptions of the model: (i) the growth rate of output follows closelythe rate of infrastructure formation and (ii) private capital formation also followsthe rate of infrastructure formation but adjusts with a delay.