As they worked north into Guanajuato, the mines became newer, shallower, more slapdash—typically these were owned by individual prospectors. More and more, the workers were free men. But this country had been settled long enough that some towns had been built, churches erected, and families moved in. It was in one of those towns—which a generation earlier had marked the absolute northern boundary of civilization—that they paused for a day to make a grand reckoning.