This weekend, millions will cross 66,000 bridges that the federal government has deemed "structurally deficient," meaning key elements are in poor condition. The Washington state bridge collapse that spilled two cars into the Skagit River could give Americans pause as they hit the roads for Memorial Day holiday travel.  Elaine Thompson / AP The north end of the Interstate 5 bridge crossing the Skagit River lies collapsed in the water on Friday, in Mount Vernon, Wash. A truck carrying an oversize load struck the four-lane bridge on the major thoroughfare between Seattle and Canada, sending a section of the span and two vehicles into the Skagit River below Thursday evening. A truck is removed May 27 from the wreckage of an Interstate 5 bridge over the Skagit River in Mount Vernon, Wash. That bridge, which was built in 1955 and collapsed May 23, was not structurally deficient. "We don't expect an epidemic of collapses — that's the extreme," said Dan Goldberg, communications director for Transportation for America, a coalition that identified the busiest deficient bridges in the nation in a 2011 report.  Visualizing the numbers 
 
 Did you know that in another ten years, one in four bridges will be 65 years old or older? Money previously targeted for bridge repair was rolled into a new National Highway Performance Program, which can be spent only on highways that are part of the National Highway System, which includes interstates and major state highways. "The states are closer to the problem," he says.
– If this story didn't already cause you to develop a mild case of gephyrophobia, then this one may do the trick: Some 11% of America's bridges are structurally deficient and in need of repair, according to a new report from Transportation for America. It's a stat made more serious when you consider this next one: 260 million trips are made across the 66,405 problematic bridges each day. As USA Today explains, these bridges aren't necessarily dangerous, they just need a lot of work, which has been priced at $76 billion by the Federal Highway Administration. That amount will just get larger as the years pass. These bridges are, on average, 65 years old, and in 10 years, the number of "senior citizen" bridges will be one in four. "You're seeing the aging of the system," says a co-author of the report. "It really does parallel the [aging of] the Baby Boomers in a startling way." Congress recently eliminated a dedicated bridge repair fund, meaning "bridge repair now must compete with other transportation needs," the report states. Rather than "an epidemic of collapses," the more common consequences of the aging bridge system will be things like more large potholes and closed lanes, the co-author tells NBC News.