Hillbilly Parade
(n) A line of broke-down 15-year-old pickup trucks driving 10-under the speed limit, or slower, in the left lane on a divided interstate highway. Frequently the pickup behind is mere inches from the pickup in front. You may see the driver (typically male) shouting angrily through his toothless lips.
I couldn't pass for 30 miles when I was driving in Kansas, due to the Hillbilly Parade in the left lane.