The good news first: If you think you're commute isn't as bad as it was six years ago, you're probably right, according to an annual study that attempts to measure how long Americans spend stuck in traffic.

And...that's about it for the good news.

The bad news? Traffic tie-ups will grow in the next few years, and with them the cost to motorists in lost time and wasted fuel — especially around the nation's largest cities with the worst delays.

The annual report by the Texas Transportation Institute draws from a network of sensors that measure traffic speeds on most major roadways across the nation every 15 minutes. That data shows while backups aren't as bad as they were in 2007 before the national recession, they still cost $121 billion a year, and waste enough gasoline to fill the New Orleans Superdome. For the typical rush-hour commuter, those backups take 38 hours a year — nearly a week of work or vacation — and require planning 60 minutes to complete a trip that takes 20 minutes in light traffic.

Top 10 Cities With Worst Traffic Delays

It's no surprise that the nation's largest cities have the worst traffic, but size alone doesn't automatically mean more delays. Drivers in Phoenix, the large city with the best traffic flow, have about as much wasted time per year as those in Louisville or New Haven, Conn. And smaller towns don't lack for backups; Nashville and Denver offer as much downtime behind the wheel as Miami and Dallas.

While New York, Los Angeles and Atlanta break into the top 10 as expected, no city comes close to the traffic nightmare known as Washington, D.C. The reasons stem from the same mix of geography and historic preservation that makes the region the worst city for traffic accidents: With far fewer city-splitting freeways than other metropolitan areas, traffic must flow either onto the eternally clogged Beltway or twisting surface roads. The region's mass transit systems work to capacity — but have started to show strains, like when an overfilled train trapped several hundred riders underground for two hours last week.

The TTI researchers say based on the trends they see, the cost of congestion nationwide will swell to $199 billion in 2020. Their prescriptions: More of everything cities already do to reduce delays, from better public transit to higher tolls for peak commuting hours. Otherwise, we're all stuck.