Having a front-row seat for the Great Houston Evacuation of Hurricane Rita, I have to agree with this. Over two million people tried to get out of the city, blocking roads for three days before the hurricane. Some observations:

1. Mayor Bill White did ask people to leave behind their material goods and take those without cars instead. Some people listened, some did not.
2. Most families here own two vehicles and took both, adding to the gridlock.
3. A bicycle would have been traveled faster than the cars, at least until you were run over by a crazy driver. People were racing down shoulders, through ditches, and anywhere else they thought they might possiblely get their vehicle through.
4. Thousands of cars here left in parking lots and along the sides of the freeways after they broke down, overheated, or were otherwise abandonned. These cars were then broken into and stripped.
5. If you have kids and pets there's no room for neighbors anyway.

-Blast