There are more than 23,000 bridges in Iowa, and the American Society of Civil Engineers says the state still has the highest number of structurally deficient bridges in the country.Of the 4,200 bridges on the primary system, meaning interstates and major highways, there are just 23 in poor condition. But Iowa has 18,136 bridges in its 99 counties. Of those, 24% are in poor condition, according to the Iowa County Engineers Association Service Bureau data shared with KCCI Investigates."They're still safe to drive across," said Brian Moore, the service bureau's director. "In no way are there any imminent problems."KCCI Investigates even found one first built as a railroad bridge in 1878. The span just outside Harvey, Iowa, in rural Marion County, is wide enough for one lane. It goes over the Des Moines River. Its estimated daily use is 21 cars. Signs ahead of it do warn it has a weight restriction.Bridges do wear out, often after 50 to 75 years of use, Moore said.Iowa had a surge of bridge building in the 1950s, 60s and 70s, he said. That's why we're seeing that number of poor county bridges. The infrastructure is expensive. In 2024, $100 million was invested in repairing, rehabbing or replacing them. "Some of the biggest challenges are just the pure number of bridges out there," Moore said. "As we know, budgets are always getting tighter; expenses are always getting higher."Some of these bridges have to bear heavy loads when farming and grain products are transported across our state.When needed, leaders put weight restrictions and signage in place."Trying to prioritize the bridges — even though there are a lot of county bridges out there that are on lower-volume roads, we still have to maintain them at a higher level because of our agricultural products," Moore said.Counties visually inspect the bridges every two years. They also repair and maintain them, even for a handful of drivers."Of the 4,000 bridges that are on county roads that are considered poor, over half of them see fewer than 35 vehicles per day," said Jim Nelson, the director of the Bridges and Structures bureau of the Iowa Department of Transportation.Iowa's ranking in the current bridge report is partially because of how many bridges the state has.KCCI Investigates asked traffic experts: Why does Iowa have so many bridges?"Everything was built on a mile grid," Moore said, adding, "All the rivers and roads we have."Repairs come in about 10 year cycles, the experts said. In 2024, 268 county bridges were repaired or replaced that year. But 259 bridges were newly categorized as "poor."That's a net improvement of nine bridges statewide, Moore said.Iowa State University graduate John Marvig has photographed and visited 800 bridges in Iowa, mostly railroad bridges."I like to see these preserved specifically like the trusses, the stone bridges," he said. "I'm a realist. Sometimes, they do need to be replaced. But one like Harvey, you know, it would be a real shame if they replaced that, especially with the limited traffic it carries."GET THE FACTSThis story is part of a larger project this year across all our Hearst Television stations and national units. We're taking a deeper look at the condition of infrastructure — including bridges and roads — in our region and across the country to Get the Facts on problem areas and trends, get answers and track the actions being taken to ensure these critical structures remain operation and safe.Missed a story? Want to dive deeper? See all the coverage below.National investigations, data stories and video explainersPotholes wreak havoc. Here’s how cities and innovative technology pave a better futureThe Francis Scott Key Bridge Collapse One Year LaterThe Interstate Highway System soon turns 70: How it transformed America and the urgent need to modernizeInteractive: A look back at the timeline of the Key Bridge collapseWhen disaster strikes: 5 of America's most destructive infrastructure failuresGet the Facts: What's the condition of bridges in the US?Impact stories from around the countryKMBC: ‘Clerical error’ brings focus on rural Kansas bridges in need of repairWMUR: Interactive look at bridge conditions in New HampshireKHBS: MAPS: Arkansas bridge conditions across the stateWBAL: NTSB issues scathing review of MDTA over Key Bridge vulnerabilityWBAL: Key Bridge Disaster: Reflect, Recover, Rebuild (Full Documentary)PHNjcmlwdCB0eXBlPSJ0ZXh0L2phdmFzY3JpcHQiPiFmdW5jdGlvbigpeyJ1c2Ugc3RyaWN0Ijt3aW5kb3cuYWRkRXZlbnRMaXN0ZW5lcigibWVzc2FnZSIsKGZ1bmN0aW9uKGUpe2lmKHZvaWQgMCE9PWUuZGF0YVsiZGF0YXdyYXBwZXItaGVpZ2h0Il0pe3ZhciB0PWRvY3VtZW50LnF1ZXJ5U2VsZWN0b3JBbGwoImlmcmFtZSIpO2Zvcih2YXIgYSBpbiBlLmRhdGFbImRhdGF3cmFwcGVyLWhlaWdodCJdKWZvcih2YXIgcj0wO3I8dC5sZW5ndGg7cisrKXtpZih0W3JdLmNvbnRlbnRXaW5kb3c9PT1lLnNvdXJjZSl0W3JdLnN0eWxlLmhlaWdodD1lLmRhdGFbImRhdGF3cmFwcGVyLWhlaWdodCJdW2FdKyJweCJ9fX0pKX0oKTs8L3NjcmlwdD4=