Within 100 miles of Sacramento, Calif., more than 1,400 new electric and plug-in hybrid vehicles are available for sale.
It's a different story in Boston, where fewer than 150 new electric or plug-in hybrid vehicles of any make were available within 100 miles of the city center in a recent search on Cars.com.
What explains such a stark difference?
According to Matt Solomon, transportation manager at Northeast States for Coordinated Air Use Management in Boston, it's the "travel provision" in California's zero-emission vehicle rule followed by nine other states, including Massachusetts.
The California rule requires automakers to sell more zero-emission vehicles in higher numbers each year. The travel provision allows an EV sold in any of the 10 states that adhere to the California zero-emission vehicle mandate to count toward an automaker's EV sales requirement in each of the ZEV states.
The provision took effect in 2004, six years before the Nissan Leaf became the first EV powered by lithium ion batteries to hit the mass market. It was aimed at aiding EV deployment in the market's infancy, but, Solomon says, it has allowed manufacturers to concentrate their EV allocations in California.