We put ashore a well-dressed lady and gentleman, and two well-dressed, lady-like young girls, together with sundry Russia-leather bags. A strange place for such folk! No carriage was waiting. The party moved off as if they had not expected any, and struck down a winding country road afoot.

But the mystery was explained when we got under way again; for these people were evidently bound for a large town which lay shut in behind a tow-head (i.e., new island) a couple of miles below this landing. I couldn't remember that town; I couldn't place it, couldn't call its name. So I lost part of my temper. I suspected that it might be St. Genevieve—and so it proved to be. Observe what this eccentric river had been about: it had built up this huge useless tow-head directly in front of this town, cut off its river communications, fenced it away completely, and made a 'country' town of it. It is a fine old place, too, and deserved a better fate. It was settled by the French, and is a relic of a time when one could travel from the mouths of the Mississippi to Quebec and be on French territory and under French rule all the way.

[LOTM p262-3]

From the Wikipedia Article:

By the late 19th and early 20th centuries, Ste. Genevieve also had numerous lime kilns and quarries, important to the industrialization of nearby cities. The city had numerous Africa-American families who had long been residents of the community, including people of color of partial French and German ancestry. Like the ethnic European French, most of these African-American families were members of the Catholic church in the town, and some were educated and property owners. Some had also been French speakers in the colonial period.

As the lime kilns and quarries were expanded, African-American migrant workers, mostly men, came from Tennessee, Mississippi, and Arkansas to take jobs in these industries. They tended to belong to Protestant sects, if they were religiously affiliated. From quite different cultural backgrounds, the two groups of African Americans did not intermingle much. The migrant workers lived in poorer areas of town or outside in company housing. They tended to congregate in a neighborhood referred to as The Shacks. [3]