“It’s always easier to defer new construction than to stop paying people who are on the payroll or the welfare rolls,” he said. “A lot of states are under real stress.”

Governments have cut back most sharply on new construction projects. Even so, the nation’s existing infrastructure continues to age and deteriorate.

The average road surface was 28 years old in 2015, up from 23 years old in 2000. Schools, power plants and airports also are getting older. Slower population growth means less demand for new construction — but also fewer tax dollars for repairs.

Arizona has reduced spending on public construction every year since 2007. State lawmakers, reluctant to raise taxes, have diverted money from highway work to pay for public services like Medicaid and prisons. One Arizona county, Navajo, has shifted from aiming to repave roads every 20 years to repaving every 40 years.

Roads are the largest category of public works, accounting for about a third of annual public works spending. The federal gas tax, at 18.4 cents a gallon, is the largest source of funding for those projects, but it is not indexed to inflation and has not been raised since 1993. It would need to be 31 cents a gallon to restore its buying power.

Chris Spear, the president of the American Trucking Associations, said his group had testified before Congress at least 19 times since 2006 in favor of raising the tax.

But the price of gasoline has outsize importance in the American psyche, and Congress has demonstrated an extreme reluctance to consider a gas tax increase.