Traffic rolls along Interstate 25 in northern Colorado. 

(AP/David Zalubowski)

If it seems like traffic in Denver is getting worse, there's a reason for that. It is. 

Metro area drivers spent an average of 49 hours stuck in traffic last year, according to Texas A&M's 2015 Urban Mobility Scorecard. That's three hours worse than 2011, good for 19th place among U.S. cities. 

And what's to blame? The improving economy, for one.

"During the recession we saw jobs go away. We also so congestion decline. But now, with the economy coming back, we’re also seeing congestion come back as well," said the report's co-author Tim Lomax.

The report calculates the cost of Denver’s congestion as $2 billion in wasted time and fuel. Lomax said the total economic impact is even greater when things like missed shipments and meetings are taken into account.

"There’s an awful lot of this congestion effect that we don’t really have a measure for," he said.

Telecommuting, living closer to work, taking mass transit, and building more roads could help ease traffic, Lomax said. 

Washington, D.C. was rated the worst traffic city, with about 82 hours of lost time per commuter. Rounding out the top five were Los Angeles (80 hours), San Francisco (78 hours), New York (74 hours), and San Jose (67 hours).