Mary Hill

About Mary Hill (Edit profile)

Professor Hill earned her Ph.D. at Princeton University. She most recently served at the U.S. Geological Survey as the chief of Modeling and Uncertainty of Complex Groundwater Systems in the national research program in Boulder Colorado. Her research interests include using hydrologic and environmental data, computer modeling, and uncertainty assessment to inform resource management and public policy (


Mary Hill, Brian D. Taylor and Martin Wachs

Prior to 1923 California, like most states, financed highway construction and maintenance by issuing general obligation bonds. By the early ’20s direct appropriations for highways and interest payments on the bonds had risen to more than 40 percent of the state’s budget. So in 1923 California adopted a new system of highway finance using earmarked user fees, in particular the per-gallon fuel tax. Before long all fifty states had similar user taxes, as did the federal government.

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