"Dixie" generally refers to states south of the Mason-Dixon survey line where slavery was legal. This map's concept of Dixie includes some areas above that line and excludes some areas inside it, like most of Texas and Missouri. "The Foundry" seems like a euphemism for the more commonly used term "Rust Belt." It's an area that traditionally has had lots of heavy industry, but has largely been in economic decline in the last 20-30 years.