A total of 54,259 of the nation’s bridges are rated "structurally deficient," and vehicles cross these compromised structures 174 million times every day, according to a newly released analysis of the U.S. Department of Transportation’s 2017 bridge inventory database.

The analysis, released by the American Road and Transportation Builders Association (ARTBA), noted that these structurally deficient bridges — if placed end-to-end — would stretch 1,216 miles. That’s nearly the distance between Miami and New York City. The average age of a structurally deficient bridge is 67 years, compared to 40 years for non-deficient bridges. 

The 1,800 structurally deficient-rated bridges that are a part of the Interstate Highway System are crossed 60 million times daily, according to ARTBA.

To help ensure public safety, bridge decks and support structures are regularly inspected. They are rated on a scale of zero to nine, with nine meaning the bridge is in excellent condition. A bridge is classified as structurally deficient and in need of repair if the rating on a key structural element is four or below. While these bridges may not be imminently unsafe, they are in need of attention.

Iowa (5,067), Pennsylvania (4,173), Oklahoma (3,234), Missouri (3,086), Illinois (2,303), Nebraska (2,258), Kansas (2,115), Mississippi (2,008), North Carolina (1,854) and New York (1,834) have the highest number of structurally deficient bridges, according to the analysis. The District of Columbia (8), Nevada (31), Delaware (39), Hawaii (66), and Utah (87) have the fewest.

At least 15% of the bridges in six states — Rhode Island (23%), Iowa (21%), West Virginia (19%), South Dakota (19%), Pennsylvania (18%) and Nebraska (15%) — fall in the category of structurally deficient.

The pace of improving the nation’s inventory of structurally deficient bridges slowed this past year, ARTBA said. But it’s down only two-tenths of a percent from the number reported in the government’s 2016 data. At the current pace of repair or replacement, fixing all of them would take 37 years, said Dr. Alison Premo Black, ARTBA chief economist.

For the Top 10 list of most-traveled deficient bridges by state, click here. 

For state-by-state rankings, click here.