I just saw a commercial that says children must use a booster seat until they are 4'9" tall.
Um, I am 4'11" tall. My two female first cousins are an inch shorter than I am. I don't know about them, but I got that last couple of inches in college. So, I reckon I would have ridden in a booster seat until I was 16 years old -- when I was a senior in high school -- under that rule.
Wow. Imagine the dates I would have had dragging along my booster seat (I didn't date much in high school as it was cause I was not *that* chick, believe me) every time someone picked me up.