Missouri in The Unvanquished (Location)

In the chapter "Skirmish at Sartoris" Bayard refers to "the two Burdens from Missouri" who are in Jefferson to help the newly emancipated slaves vote in a local election (199). As Light in August confirms, the Burdens did live in Missouri before coming to Yoknapatawpha, but in the chapter "An Odor of Verbena" Drusilla calls the Burdens "northerners" (223). In Light in August the older Burden was born in New England, but it's not clear that Drusilla could have known that. Missouri was a slave state, but did not join the Confederacy - perhaps to Drusilla that makes it a 'northern' state.