Can traffic be an election issue? Two Democrats running for governor hope so.

Inbound traffic on the Massachusetts Turnpike. –Aram Boghosian for The Boston Globe

For generations, standstill traffic has been as central to Boston’s identity as clam chowder and the Red Sox.

So why hasn’t it combined with another favored pastime — politics — to become a dominant issue in election campaigns?

Despite vexing hundreds of thousands of commuters every day, traffic congestion has rarely featured in statewide elections. Even when transportation was near the top of the public agenda in the era of highway expansion and during the Big Dig, it was rarely the central issue driving voters to the ballot box.

The two Democratic candidates for governor, Bob Massie (left) and Jay Gonzalez (right), are keying in on transportation in their bids to unseat Charlie Baker. —John Tlumacki/Globe Staff/File