I just learned about the TomTom Traffic Index today. It covers 404 cities across 58 countries, and uses anonymized traffic data from more than 600 million drivers (people who use TomTom's tech) to come up with a list of the cities with the worst traffic congestion.

Here's the global top 10 (for 2021):

And here's the North American top 10 (also for 2021):

The way to interpret these congestion level percentages is to think of them as additional time over and above baseline free-flowing traffic times. For example, a 62% congestion level for Istanbul, means that a trip that would take 30 minutes without any traffic congestion, will instead take, on average, 18.6 minutes longer (0.62 x 30 minutes).

We all like to complain about traffic in our home city, but these percentages certainly help to put things into a global perspective.