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2. Future Financing Options to Meet Highway and Transit Needs
3. Colby S. L., Ortman J. M. Projections of the Size and Composition of the U.S. Population: 2014 to 2060. U.S. Census Bureau, 2015. https://www.census.gov/content/dam/Census/library/publications/2015/demo/p25-1143.pdf. Accessed July 22, 2019.
4. Federal Highway Administration (FHWA). Highway Statistics2015. https://www.fhwa.dot.gov/policyinformation/statistics/2017/. Accessed July 27, 2019.