How much does 1 cubic yard of dirt weigh?

Question:I am going to haul some dirt in my truck. I can figure out the exact volume of my cargo area but was wondering if there is a basic rule of thumb as to how much a cubic yard of dirt weights. This is "clean" topsoil type dirt with no rocks or other garbage in it.
Thanks-

Answers:
A "yard' is a lot of weight.just under a ton.