According to the Environmental Protection Agency, transportation accounts for 27% of total U.S. greenhouse emissions each year, placing it ahead of agriculture, commercial use, residential use, and electricity generation. Whenever possible, it is most sustainable to walk, bike, and use public transportation to get around. Additionally, shifting towards electric vehicles can help reduce the carbon footprint associated with transportation as our electricity grid is powered more and more with renewable energy.

Below is a chart that shows the relative energy intensity of various methods of transportation taking into consideration the average number of passengers per vehicle. We share this to demonstrate how impactful it can be to maximize the number of people traveling in a vehicle. Carpooling makes driving a personal car more efficient; similarly, a full bus is more efficient per passenger mile than one with few riders.

Per passenger mile efficiency of different transit modes. Transit Bus is least efficient because of average ridership.

Graph of energy intensity from the Center for Sustainable Systems Personal Transportation Fact Sheet.