Answer: Beijing, China

The next time you’re stuck in a traffic jam after work, be thankful you aren’t on your way home from work in China. More specifically, that you never found yourself on your way home from work on the China National Highway 110 in mid-August of 2010.

On August 14, 2010, a sort of chain-reaction traffic jam started that spiraled out of control. Traffic backed up for a few miles, then a dozen miles, but the gridlock ultimately extended for sixty miles down the China National Highway 110 and the Beijing-Tibet Expressway. Traffic slowed to such a crawl that most of the vehicles caught in it were moving only half a mile per day. The traffic jam lasted for 12 grueling days and thousands of people spent five days or more babysitting their car on an agonizing cross-country crawl.

So how did the jam start? There wasn’t a single cause but instead a perfect storm of small problems adding up to a massive jam. Heavy construction along Highway 110 had reduced its capacity to 50% in many places. Long-haul truck traffic was up significantly to meet demands the rail system couldn’t handle (and many of those trucks were avoiding inspection stations on other highways because their loads were too high and their paperwork improper). Combine that with expected car troubles and routine breakdowns (but nowhere to move the decommissioned vehicles) and you have a recipe for a traffic jam that spanned the countryside.