U.S. alternative fuel vehicle laws and incentive additions by technology type

* Aftermarket conversions were not recorded as a separate category until 2012.
** The source specifies that "after 2008, the "Emissions" category was moved to the "Other" category, and the "Blends" category was moved to the "Ethanol" or "Biodiesel" categories."
*** Neighborhood EVs were not recorded as a separate category until 2014.

The source specifies that "additions include any incentive or law that was added to the Alternative Fuels Data Center, usually in the same year that it was enacted or brought into force. Counts include incentives/laws enacted by all 50 states and the District of Columbia, including legislation that has since expired."

The electric vehicle category includes both battery-electric and plug-in hybrid electric vehicles