THE most pressing problems can sometimes be the dullest — until they force their way into our attention in an instant.

On Aug. 1, the bridge carrying Interstate 35W over the Mississippi River buckled and broke. Thirteen people were killed. More than 100 were injured.

Afterward, we learned the frightening facts: 160,570 of our bridges are in just as dangerous a shape; a third of our roads are in poor or mediocre condition; some of our biggest cities depend on water and sewage systems over a century old.

With every bursting pipe, potholed road and derailed train, the conclusion became inescapable: America’s backbone is decaying.

It wasn’t always this way. Year by year and ton by ton — from the great railroads to tens of thousands of miles of Interstate — great American engineers built the foundations of our prosperity.

Why are we leaving so little for our future? Reliable infrastructure keeps economies growing and the entrepreneurial spirit vibrant.

Last summer, Senator Chuck Hagel and I proposed a National Infrastructure Bank. I hope it gets the attention it deserves on the campaign trail. It’s encouraging that Barack Obama and Hillary Clinton are both co-sponsors. John McCain should be, too.

The Infrastructure Bank would unite the public and private sectors to complete large-scale works. Funds would go to the most qualified projects, not those with the most political clout. Every $1 billion spent on highways and transit projects would create about 47,500 jobs.

This issue may never bring an audience to its feet, but it shouldn’t have to.

On Jan. 21, the 44th president will face volumes of pressing challenges. Reinventing our infrastructure ought to be on Page 1.