The natural gas fuel delivery infrastructure required to support a fleet of vehicles large enough to displace 2 million bbl/day of petroleum consumption was estimated. The number and types of vehicles required to use this amount of natural gas was defined based on operational characteristics and technical feasibility. Existing natural gas pipeline and storage capacity was assessed and additions estimated. Natural gas refueling stations to serve the natural gas vehicles defined were estimated. The total cost of the natural gas infrastructure additions was estimated. The institutional and infrastructural barriers to widespread use of natural gas were identified and lead times to overcome them were estimated.