I may be able to chime in o the "lost mixed society" idea. I'm Creole and from Louisiana...we were always "free peoples" and prior to the "Louisiana Purchase" the territory was considered foreign to "Americans". Now at this time we did not like "Americans" and thought then to be a bit barbaric and uncultured. We did not like them moving into our lands and neighborhoods and tried our best to separate ourselves, continue using French/Creole and keeping them out of government, etc. Now there's writings from the "American" perspective saying when they came into the newly acquired lands they were astonished and outraged at what they saw: people of all races openly interacting with one another and holding equal positions to one another in society. They reported lavish living on par with European kings with a lot of decadence and fine clothing. Relationships between different races out in the open and negroes and whites dancing and drunk with one another in the streets....the "Americans" could not have this, they reported back and the rest is history. Free Creoles, blacks, etc slowly got pushed out if government, their businesses taken, rights taken, laws changed, French language outlawed in most cases and removed as the spoken language of the courts/government....wars, replacement, Jim Crow laws, census changes and many previous "race options" disappearing from it and everything getting consolidated to "black/colored and white". Most of the history from that time isnt spoken about or widely known. West of the Mississippi was a totally different place and country. So yes there was a much different and mixed society prior to the American takeover of the "West".