Traffic is more than just a nuisance: It eats valuable time spent with our family and friends, it increases our stress levels, and with the boredom leading to a rise in cell phone usage, it can be dangerous. And it's only getting worse, according to a new study by TomTom navigation. With congestion trending higher year-over-year, we can expect to spend even more of our day inhaling exhaust fumes while Ryan Seacrest spews love advice over the radio. And that's not a good thing at all.

By analyzing millions of TomTom users' travel times over many more millions of miles driven, the company has not only put together a list of the most congested cities in North America (and Hawaii), but dissects how different times and days affect the traffic's flow -- as well as a glimpse at how each city is evolving over the years. We reported TomTom's July 2012 study, and since that time, if you live in San Francisco or New York, you may be noticing your commute significantly worsening, whereas those in warmer climates -- like Miami, Tampa and Houston -- might be feeling some needed relief.

The TomTom North American Congestion Index

Los Angeles ranking as number one arrives with little surprise, but by comparing this year's report to the one from mid-2012, the increase of 3-percent in congestion is entirely down to a 6-percent increase in highway traffic. Non-highway backup has actually decreased by 3-percent. Still, for every hour spent on the road in peak traffic, a driver will lose on average 39 minutes. Over the course of year, if you have a 30 minute commute, you will spend a whopping 90 hours sitting in smog-infested misery.