It's still not entirely clear what caused I-5 bridge over the Skagit River in Washington to collapse Thursday night. Nor is it clear, despite media reports, how strong the bridge was before it broke. What is clear is that, had the state needed to repair it, getting federal money to do so would be an uphill climb.

To demonstrate the steep drop-off in Business Insider created a graph, using data from the Federal Reserve, showing spending on public construction. We took the same data and made it a bit easier to read.

In raw dollars, the decline is obvious. From a peak of about $325 billion in March 2009, the monthly amount has plummeted to $258 billion — a big number to upgrade your house, but less so for the entire country.

But when you compare spending to the entire economic output of the country — how much of what we make that's spent on public construction — the picture becomes more stark. We haven't spent this little of our economic output on public construction since before 1993.

This drop has been something of a hobby-horse for the president. Five times over the last five years he's advocated for increased spending on infrastructure— only once, during the stimulus, with any success.

Again: It's not clear that the bridge in Washington needed federal help. A 2011 list of "Structurally Deficient Bridges" from the Washington Department of Transportation includes the Skagit River bridge, noting that the deficiency was found in the bridge's deck. The remedy for the problem, however, indicates its severity: "Monitor thru Inspection."

Mother Jones's Clara Jeffery tweeted this helpful glossary from the Iowa DOT, explaining what that means.

A bridge sufficiency rating includes a multitude of factors: inspection results of the structural condition of the bridge, traffic volumes, number of lanes, road widths, clearances, and importance for national security and public use, to name just a few. …

The fact that a bridge is classified under the federal definition as “structurally deficient" does not imply that it is unsafe. A structurally deficient bridge, when left open to traffic, typically requires significant maintenance and repair to remain in service and eventual rehabilitation or replacement to address deficiencies. To remain in service, structurally deficient bridges are often posted with weight limits to restrict the gross weight of vehicles using the bridges to less than the maximum weight typically allowed by statute.

Emphasis in the original. A 2010 inspection apparently found that the bridge was "functionally obsolete" with a sufficiency rating of 57.4. Both sound bad, but neither necessarily is. "A functionally obsolete bridge," the Iowa DOT glossary explains, "is one that was built to standards that are not used today. These bridges are not automatically rated as structurally deficient, nor are they inherently unsafe." And as the Associated Press noted Thursday night, over 750 bridges in Washington state alone have lower sufficiency ratings.

Not that this information makes the state of the bridge strong. Watching not-the-worst bridge collapse is hardly reassuring, particularly since the American Society of Civil Engineers gave the state's bridges a C- earlier this year. To remedy all of the problems the group found across the country's infrastructure would require an additional investment of $3.6 trillion by 2020.

Don't hold your breath.