At the end of June, Washington state had 24,624 plug-in electric vehicles registered. Most were in outlying areas of Seattle, with King County accounting for over half those vehicles.
The distribution remains more sparse in the eastern part of the state. Some of those counties overlap with the service territory of Avista Corporation, a utility with natural gas and electric operations in Washington, Idaho and a few pockets of Oregon. Avista estimates there are just 600 electric vehicles in its Washington territory.