Wow - if the mail cost $1 to $5 per ounce, it was just something the rich could do. According to one inflation calculator online, $1 in 1860 is equivalent to $28.69 today. So when we were still using snail mail, we didn't realize what a good deal we had.
I was thinking the same thing, that it must have been expensive. Thanks for looking that up! The high cost is a fact that I don't remember learning about the Pony Express.