Here on the Columbia River, officials in Portland and Vancouver said they had no illusions that they could build, on their own, a major interstate highway bridge on a major freight and passenger corridor that runs from Canada to California and carries an average of 124,000 vehicles a day. Even the much smaller Skagit River Bridge, which collapsed in May on Interstate 5 about four hours north of here, will cost more than $15 million to replace.

But the officials say that they can at least start breaking the eggs to make the omelet. The old plan had a sense of inevitability, they said, that nothing could be changed for fear of unwinding the many delicate political compromises built in over the years. A new plan would put everything back on the table.

Even a mass transit element, which Portland had insisted on before, could be rethought, Mr. Alpert said, if, for example, an existing freight rail bridge over the water could be used for passenger transit in a new plan. Mr. Leavitt, a civil engineer who said he leans to the right politically — though the Vancouver mayor’s office is nonpartisan — said he bristled at what he says was hostility toward liberal Portland by conservatives in the Washington State Legislature. In a completely interconnected economy, he said, a blow against Portland is a blow against Vancouver.

The truth, transportation data suggests, is that the entire Pacific Northwest is developing its own unique transportation profile.

Since 1990, for example, per capita gasoline use has fallen in many states. But Washington and Oregon were at the front of the pack, with greater percentage declines than any state but Nevada, the Sightline Institute, a research and environmental advocacy group based in Seattle, reported in an analysis of federal and state data. And Nevada’s decline was mostly driven by the rapid growth of Las Vegas — more people concentrated in a city without the need to drive vast distances.