Cities in California, Washington, Georgia, Oregon and Hawaii mostly dominate this chart, which shows the Top 30 U.S. cities for market share for plug-in electric cars.

Outside of the 5 states listed above, only Colorado makes a showing with Boulder.

The premise behind the International Council On Clean Transportation source article is that the electric car future has already arrived, at least in some cities.  ICCT states:

"We've been looking at data from U.S. cities, and here's one very noticeable finding: distribution of EV sales is very uneven across the top 30. The chart below shows the top 30 metropolitan areas in the US, based on the share of new light-duty vehicles that are plug-in electric (including plug-in hybrid electric and fully battery electric vehicles). California cities dominate the list, with 18 of top 30 US cities. San Jose is far out in front, with about 1 in 10 new vehicles being plug-ins. After California, Washington, Oregon, Georgia, and Hawaii come next with multiple high-EV-uptake cites. The top 10 cities have from 4 to 13 times the electric vehicle uptake of the national US average."

ICCT concludes:

"We could very well be seeing the future of transportation in the leading California, Oregon, and Washington cities. If we continue to learn from and embrace what’s working (and discard what’s not), the progress toward an electric fleet could continue – more quickly and more evenly."

Source: ICCT