Transportation planners, engineers, and administrators face the difficult tasks of prioritizing and justifying proposed investments in transportation infrastructure, particularly as government budgets tighten and alternative investments compete for public funding. One means by which professionals can prioritize and justify large transportation investments is by describing how a proposed project will impact an area’s economy in terms of creating new jobs, raising aggregate income, and increasing business revenues. The report begins by examining the general impact of transportation investments on economic development. Then it surveys various methods and tools that have been proposed for estimating economic impacts. Among these, the TREDIS economic impact model is selected and used to estimate the economic impacts of a current interstate highway project in Texas. / text