But while drivers report line-ups at some heavily-used stations along Interstate 5, other electric-vehicle charging sites on the state network are rarely getting used, the data show.
Since May 2012, when the first fast-charging station began operating in Washington as part of the so-called West Coast Green Highway, drivers have used the state's 14 charging stations more than 10,000 times. Monthly usage for all those sites doubled to 1,125 charging sessions last September from 528 the previous September.
Drivers hit stations in Bellingham, Burlington and Tumwater the most, while there was much lighter traffic along the I-5 network at Castle Rock and Ridgefield. Charging stations along Highway 2 in Wenatchee and at a rest stop along I-5 in Ferndale saw the least usage - on average about 10 sessions each month over the past year.
Fast charging stations have been installed along Interstate 5 and other corridors in Washington and Oregon as part of an ambitious plan to allow drivers of electric vehicles to cruise the 580 miles from the southern border of Oregon all the way to Canada.
"The usage is steady and strong and the numbers keep climbing," said Tonia Buell, a state transportation spokeswoman. The purpose of the fast charging network is to give electric vehicle owners the confidence to know they can find public-access charging, even for longer-distance travel, she added.
"The actual number of times the stations are used is not the best indicator of performance," Buell said, noting there are now more than 5,000 plug-in electric vehicles registered in Washington.
In Oregon, 34 charging stations are up and running along I-5, Highway 101 and other major routes, said state transportation spokeswoman Ashley Horvat. Since the first ones opened in March of 2012, drivers have charged nearly 10,000 times.
Miles Erickson, 35, who lives in Everett and owns a Nissan Leaf all-electric vehicle, said he wants to see more of fast chargers.
"There's absolutely demand for it," said Erickson, a college instructor. He said he has had to wait about 10 times for other drivers to finish charging in recent months, which makes it hard to plan longer trips if he has to get to a destination by a certain time.
Drivers are able to fully charge electric vehicles in less than 30 minutes with level-3 DC fast-chargers, or in several hours with level-2 medium-speed chargers.
He said the state built its network to make it possible for someone to drive long distances, but the reality is that more people have bought electric cars and need these stations.
Washington received $1.6 million in seed money from the U.S. Department of Energy with American Recovery and Reinvestment Act dollars. The transportation department hired contractor AeroVironment to install fast-chargers along I-5 between Everett and the Canadian border and between Olympia and the Oregon border.
The network was designed to complement The EV Project in the Seattle area. That partnership between the federal government and Ecotality was separately working to install hundreds of charging stations from Everett to Olympia, and elsewhere in the country.
But Ecotality filed for bankruptcy in September. It only installed about half of the fast charging stations planned in the Puget Sound region, Buell said. Ecotality had received more than $100 million in funding from the Department of Energy since 2009.