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Construction crews work on a freeway overpass along Highway 101 on March 26, 2012 in Novato, Calif. - 

Jeremy Hobson: Construction on roads and bridges around the country could grind to a halt this weekend. That's because federal transportation funding expires on Saturday, and Republicans and Democrats in the House have yet to agree on an extension of that funding.

Marketplace's Amy Scott reports.

Amy Scott: More than a million construction jobs could be on the line if Congress can't reach a deal. The Senate has already passed a $109 billion bipartisan bill that would fund transportation projects for two years. The House hasn't been able to agree on its own bill. Now Republican leaders are working on a short-term extension.

If they fail, Loren Smith with Capital Alpha Partners says it's not clear exactly how many workers could be laid off.

Loren Smith: But certainly should the highway programs be suspended on Saturday night, you would see all manner of projects stop, and that would definitely create a disruption.

If Congress can't reach an agreement, the federal government would also have to stop collecting gasoline taxes.

But don't get too excited. Smith says several states have laws that would automatically raise their own taxes if the federal tax is suspended.

I'm Amy Scott for Marketplace.

Follow Amy Scott at @amyreports