In the U.S., government entities on the Federal, state, and local levels are pushing for greater electric-car adoption in different ways.
While different regions in the country are working towards the same goal, the policies enacted to reach it--and the degree to which they're implemented--can vary significantly.
Consequently, the distribution of electric cars throughout U.S. metropolitan areas is somewhat uneven.
It tracks which U.S. cities have the most electric cars, and seeks to draw conclusions about why those cities have been more effective in promoting adoption than others.
Total plug-in electric car sales from the 25 cities studied accounted for 1.1 percent of new-vehicle sales in 2014, according to researchers.
Electric-car registrations and promotion actions in U.S. cities in 2014 (via ICCT)
They also represent 67 percent of new electric-car registrations, and 53 percent of charging infrastructure, as of 2014.
The seven cities with the highest per capita electric-car sales in 2014 were: San Francisco, Atlanta, Los Angeles, San Diego, Seattle, Portland, and Riverside (California).
These cities each had two to seven times the national average of electric cars in their jurisdictions.
The preponderance of West Coast cities perhaps isn't surprising, considering the aggressiveness with which California, Washington, and Oregon promote electric cars.
All of the top cities were found to be engaging in multiple activities to promote electric cars--from investing in charging infrastructure and granting cash incentives, to giving drivers perks like solo carpool-lane access.
Electric cars at charging stations at Disney Family Museum, San Francisco [photo: Wendy Bartlett]
In the case of California, a zero-emission vehicle mandate means certain manufacturers are obligated to build cars specifically for sale in the state, giving Californians a greater choice of models.
Researchers noted that while each city tailors policies to its specific needs, an outline of best practices is beginning to emerge.
Specifically, the "ecosystem approach" of involving a wide variety of groups--including governments, private companies, and not-for-profits--is one of the most effective ways to promote electric cars.
Electric Avenue rededication, Portland, July 2015
They're also the ideal environment for most electric cars on sale today.
Short average trip distances, lots of stop-and-go traffic, and plenty of parking spaces that can house charging stations ensure cars' relatively short ranges aren't taxed.
However, as more longer-range electric cars appear--and efforts to grow the segment continue--advocates may have to look beyond metropolitan areas.