It’s very apparent that traffic congestion is not just a problem of recurring “rush hour” delays (road use exceeds existing capacity) that exist virtually every day. Congestion occurs during longer portions of the day, and delays more travelers and goods than ever before.

Did you know that know that more than half of all congestion is non-recurring, meaning it is caused by crashes, disabled vehicles, adverse weather, work zones, special events and other temporary disruptions?

Here’s another shocker. While it may not seem so, traffic congestion has actually eased.

Last year, traffic congestion decreased about declined 30% during the peak periods on major roads in the nation’s 100 largest metropolitan areas. So finds the latest Inrix National Traffic Scorecard. Inrix is a leading provider of traffic information.

The chief reasons for this, Inrix found, was turbulent fuel prices, which led to less driving and more carpooling, and a struggling economy, which has caused a decrease in jobs.

What has stayed the same, however, is that Los Angeles, CA; New York, NY; Chicago, IL; Dallas, TX; Washington, DC; Houston, TX; and San Francisco, CA, have maintained their distinction of being the US’ most traffic-congested cities.

And what’s a consequence of traffic congestion? Road rage.

So head’s up if you’re going to be traveling through these “highly ranked” cities.