The Highway Funding Formula: History and Current Status

More than 90% of federal highway assistance is distributed to the states by formula. Between 1916, when Congress created the first ongoing program to fund road construction, and 2012, various formula factors specified in law were used to apportion highway funds among the states. After 1982, these factors were partially overridden by provisions to guarantee that each state received federal funding at least equal to a specific percentage of the federal highway taxes its residents paid. Since enactment of the Moving Ahead for Progress in the 21st Century Act (MAP-21; P.L. 112-141) in 2012, formula factors such as population and highway lane mileage have ceased to have a significant role in determining the distribution of funds. The apportionment among the states under the current surface transportation law, the Fixing America’s Surface Transportation Act (FAST Act; P.L. 114-94), passed in 2015, is not based on any particular policy objectives other than ensuring the stability of states’ shares of total funding based on their shares in the last year of MAP-21, In addition, each state is guaranteed an amount at least equal to 95 cents on the dollar of the taxes paid by its residents into the highway account of the Highway Trust Fund. Some policy-related factors used to distribute highway funds in the past are no longer in use, while other possible factors sometimes mentioned in policy discussions, such as states’ rates of population growth and projected increases in truck traffic, have never been used as formula factors. This report describes mechanism by which Federal-Aid Highway Program funds are distributed today, and includes tables comparing individual states’ shares of the FY2018 apportionment with their shares of some factors relevant to highway needs. Table 5 ranks states’ apportionments based on the apportionment amount per resident, per square mile of land area, per federal-aid highway lane mile, and per million vehicle miles traveled on federal-aid highways.