(NewsNation) — America has thousands of bridges in need of repair, but how long will it take to fix them, and how safe are they right now?

President Joe Biden and Senate Republican Leader Mitch McConnell appeared in a rare show of bipartisanship in Kentucky to tout the construction of a new Ohio river bridge. The project was made possible with funds from the $1 trillion bipartisan infrastructure package signed in 2021. More than a billion dollars was allocated to Kentucky and Ohio for the project.

It’s just one of the massive bridge projects needed to correct years of neglect, rendering thousands of America’s bridges “structurally deficient.”

Bridges are a necessary and often beautiful part of America’s infrastructure. With more than 6,000 miles of bridges from California to Maine, they’re also hard to avoid.

And more than a third of them are in need of repair.

According to a report from the American Road and Transportation Builders Association, nearly 80,000 bridges need replacing and roughly 45,000 are rated in poor condition with repairs long overdue.

“A lot of these bridges were designed for a 50 year lifespan. And so it’s really not surprising that those bridges would be deteriorating, without having the proper amount of inspection and repair programs in place,” said engineer Troy Morgan.

That could be a major problem, with American motorists and pedestrians traveling over these structures roughly 170 million times a day. They cross highways and streams, rivers, roads, and rails and disrepair and lack of proper inspections could mean an accident waiting to happen.

That’s especially true for states with the most bridges in the poorest condition. The top five states for bad bridges? Missouri, Oklahoma, Illinois, Pennsylvania and Iowa.

Morgan said that has to do with more just neglect. Massive flooding and other environmental conditions can damage bridges or increase deterioration.

“If a lot of the state has bridges that are subjected to, you know, salt spray, or an ocean environment or marine environment that may accelerate the corrosion of steel elements. Or if there’s things in temperature, you know, cold and freeze thaw cycles may cause damage to concrete. So there’s lots of reasons why a bridge may need to be repaired, say earlier than another one,” he said.

Over the years, we’ve seen what can happen when bridges collapse.

Last year in Pittsburg, at least ten people were injured when a snow-covered bridge collapsed. Rescuers formed a human chain to get victims to safety from a bus that was dangling from the collapsing bridge.

In 2018, a pedestrian bridge with known cracks collapsed onto a highway in Florida, killing six people and crushing the cars below.

Back in 2007, 13 people were killed in downtown Minneapolis when a bridge collapsed over the Mississippi river when cars, trucks and a school bus were sent plummeting into the water. 145 people were injured in the disaster.

“Fortunately, bridges collapses are rare. But the way to prevent them in the future is really robust and effective maintenance and inspection programs,” Morgan said.

Although they are desperately needed, maintenance, repair and bridge replacement projects can cause major disruptions and shutdowns to the nation’s bridges, affecting the country’s vastly intertwined transportation system and everything from commuters to supply chains.

“I don’t think that safety of our bridges is really the thing to be worried about as much as the disruption and shutdown of various routes that can then cause a bunch of maybe economic problems, social problems linked to our commutes, disrupting our supply chains, and really making our lives more difficult,” Morgan said.

The bipartisan infrastructure bill allocated an additional $110 billion in funding to repair roads and bridges across the country.