The dissertation consists of three essays: 1) Productivity growth in the transportation industries in the United States: An application of the DEA Malmquist productivity index; 2) how does a carbon dioxide emissions change affect transportation productivity? A case study of the U.S. transportation sector from 2002 to 2011; and 3) forecast of CO2 emissions from the U.S. transportation sector: Estimation from a double exponential smoothing model. The first essay reviews productivity growth in the five major transportation industries in the United States (airline, truck, rail, pipeline, and water) and the pooled transportation industry from 2004 to 2011. The major findings are that the U.S. transportation industry shows strong and positive productivity growth except in the years of the global financial crisis in 2007, 2008, and 2010, and among the five transportation industries, the rail and water sectors show the highest productivity growth in 2011. The second essay examines the effects of a carbon dioxide (CO2) emissions change on actual productivity in the U.S. transportation sector. This study finds that a CO2 emissions increase from 2002 to 2007 had a negative effect on actual productivity in the U.S. transportation sector, but the CO2 emissions reduction for 2008–2011 increases actual productivity. States mainly showing sustainable growth patterns (decrease in CO2 emissions concurrent with increasing actual productivity) experience higher technological innovation increase than an efficiency decrease. This finding suggests that fuel-efficient and carbon reduction technologies as well as alternative transportation energy sources may be essential factors to both grow transportation and slow global warming. The third essay reviews whether the decreasing trend in U.S. CO2 emissions from the transportation sector since the end of the 2000s is consistent across all states in the nation for 2012‒2021. A double exponential smoothing model is used to forecast CO2 emissions for the transportation sector in the 50 states and the U.S., and its findings are supported by pseudo out-of-sample forecasts validity testing. This study concludes that the decreasing trend in transportation CO2 emissions in the U.S. will continue in most states in the future.