The bridge was built in 1955 and has a sufficiency rating of 57.4 out of 100, according to federal records. That is well below the statewide average rating of 80, according to an Associated Press analysis of federal data, but 759 bridges in the state have a lower sufficiency score.
Democratic Rep. Judy Clibborn, who leads the transportation committee in the state House, said the bridge wasn't one that has been a focus for lawmakers.
"It isn't anything that was on our radar screen as being an issue," Clibborn said. "It is shocking that I-5 would have something happen like this."
According to a 2012 Skagit County Public Works Department, 42 of the county's 108 bridges that are 50 years or older. The document says eight of the bridges are more than 70 years old and two are over 80.
Washington state was given a C in the American Society of Civil Engineers' 2013 infrastructure report card and a C- when it came to the state's bridges. The group said more than a quarter of Washington's 7,840 bridges are considered structurally deficient of functionally obsolete.
Baker reported from Olympia, Wash.