How many Pony Express riders were killed by Indians and outlaws in the American Old West?

It was a dangerous job, as indicated by the newspaper ads that recruited riders:

“Wanted: Young, skinny, wiry fellows. Not over 18. Must be expert riders. Willing to risk death daily. Orphans preferred.”

Surprisingly, though, the 183 riders, aged 11 through the mid-40s, despite the ad, survived pretty well. Only one was killed by Indians, although his pony knew the way and continued with the mail to the next station.

For the danger, the riders were paid $100-150 a month, equivalent to about $1,900-$2,750 in today’s money.