By taxing rents, governments can avoid a trade-off between productivity-enhancing public investment and efficiency losses from raising funds. However, it is unclear whether the rents present in a growing economy are sufficient to finance the socially optimal investment. We prove that the social optimum can be attained if the income share from a fixed factor, such as land, exceeds the public investment requirement. We thus translate the Henry George Theorem from urban economics to neoclassical and endogenous growth settings: here, the socially optimal land rent tax rate is below 100 %. Our finding may address the underfunding of national infrastructure investments.