Between 1840 and 1870, a quarter of a million Americans crossed the continental United States, some twenty-four hundred miles of it

Guidebooks promised that the adventure would take no more than three to four months’ time—a mere summer’s vacation. But the guidebooks were wrong.

For many, it would mean six to eight months of grueling travel, in a wagon with no springs, under a canvas that heated up to 110° by midday, through drenching rains and summer storms.