"Orphans preferred" was the call that went out to the daring of heart when the Pony Express was organized nearly 150 years ago in April 1860. Called "The Greatest Enterprise of Modern Times," the endeavor--which lasted only nineteenth months--recruited young men willing to risk life and limb in a relay race that crossed the frontier on a route from St. Joseph, Missouri, to San Francisco, California, speeding the delivery of mail to an astonishing...