A Baltimore bridge was hit by a large freighter and then quickly collapsed, underscoring the importance of bridges in the daily lives of many Americans.

Six construction workers on the bridge are presumed dead. Drivers of the more than 30,000 vehicles that cross the bridge each day must find a new route around or across the Patapsco River.Freight traffic at the Port of Baltimore will be closed for a while, forcing many businesses to find other ways to move goods in and out of the U.S.

Although the Interstate 895 bridge in Baltimore was in good condition before the ship collision, thousands more bridges across the country are in poor condition due to aging piers, beams and critical structural components.

Here are some highlights from an Associated Press analysis of the more than 621,000 highway bridges longer than 20 feet listed on the federal government’s National Bridge Inventory.

Thousands of poverty bridges

Inspectors rate bridges using a scale of 0-9, with a score of 7 or above considered “good.” A “Poor” rating reflects a score of 4 or less for any portion of the bridge’s major components. A moderate rating is considered “fair.”

According to the federal government, approximately 42,400 bridges in the United States are in poor condition and carry approximately 167 million vehicles every day. These poor bridges are on average 70 years old.

Four out of five of these poorer bridges had problems with their substructure (the legs that support the bridge) or their superstructure (the bridge that supports the load). Ten years ago, more than 15,800 bridges were in poor condition, according to an Associated Press analysis.

Iowa has the highest number of defective bridges, followed by Pennsylvania, Illinois and Missouri.

Why do bridges collapse?

Although unusual, the collapse of the Francis Scott Bridge in Baltimore was not the first bridge to be struck by a boat. According to a 2018 report by the World Water Transport Infrastructure Association, from 1960 to 2015, there were 35 major bridge collapses globally due to ship or barge collisions, resulting in a total of 342 fatalities. Eighteen of the accidents occurred in the United States.

Although rare, a bad bridge may eventually collapse.

In January 2022, a bridge over Fern Hollow Creek in Pittsburgh collapsed, injuring but not killing passengers in several vehicles on the bridge. Federal investigators determined that the bridge’s steel legs had corroded, creating obvious holes, but inspectors failed to calculate the extent of the problem and the city failed to follow repeated recommendations.

“The collapse of this bridge was not just an act of God. It collapsed because of a lack of maintenance and repairs,” said Michael Graham, a member of the National Transportation Safety Board.

blow to economy

When a bridge closes or collapses, there are economic consequences.

In 2007, an Interstate 35 bridge collapsed over the Mississippi River in Minneapolis, killing 13 people and injuring 145 others. A state analysis estimated that Minnesota’s economy lost $60 million in 2007-08 due to increased travel times and operating costs for commuters and businesses.

Bridges in Providence, Rhode Island, and Tacoma, Washington are currently closed due to safety concerns. Nearby businesses were hit as motorists took other routes.

Marco Pacheco, who owns a liquor store on a main thoroughfare in Portugal’s East Providence neighborhood, said his business revenue has dropped 20 percent since the bridge closed late last year. But he’s more worried about the long-term consequences.

“Traffic is not going to come back right away. People have reshaped their patterns, thought processes, etc.,” Pacheco said.

Business owners in Washington have similar concerns about the indefinite closure of the Fishing War Memorial Bridge in an industrial area near the Port of Tacoma. The nearby Interstate 5 bridge offers a good alternative, but that means many motorists drive directly over the exit ramp without considering nearby businesses, such as a Harley-Davidson motorcycle shop.

“Is there a danger?” Harley-Davidson store owner Ed Wallace asked. “Yes, absolutely, it’s a very serious matter for me as a business owner.”

federal funding

A massive infrastructure law signed by President Joe Biden in 2021 allocates $40 billion over five years to build bridges, the largest bridge-specific investment in decades. Transportation Secretary Pete Buttigieg said the law already funds more than 7,800 bridge projects.

But even that would only reduce the estimated $319 billion in bridge repairs needed nationwide, according to the American Road and Transportation Builders Association.

“The bottom line is, America’s bridges need a lot of work,” Buttigieg told The Associated Press after visiting the closed Rhode Island bridge. He added: “The sooner we address issues with these vital bridges, the less likely they are to suddenly come out of service, or worse, experience the risk of collapse.”