The frontier outpost of Natchitoches was the oldest settlement in all the 828,000 square miles of the Louisiana Purchase. Natchitoches was built by France along the Texas border as a buffer against Spanish and Indian aggression. For the next century and a half, it would be the hub for colonial trade with the Southwestern tribes and then the gateway to the west for hordes of "Am?ricains" seeking new land after the Revolution. Censuses, tax lists, and...