Arose within a power vacuum during the decline of the US, as a racial panic response against the incursion of the Second Mexican-American War ("La Reconquista"). The DMS is explicitly a White supremacist regime, enforced through violence and terror. However, their territory is surprisingly stable given the circumstances, since it beats the alternative of complete chaos exemplified by Outlands.
The DMS is committed to a revival of the Rust Belt, and a culture of atavism for a lost golden age reigns. They follow a Neo-Völkisch social design.
Territory tends toward major highways, extending from the capital of Detroit as far West as Minneapolis, as far East as the West side of the Appalachians, and as far south as Kansas City, Menfis & Indianapolis. And yes, the DMS unsurprisingly serves as an interface for Menfis' slave trade.