The idea of popular sovereignty can first be found in the

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.

the border between arizona and new mexico is a thin, black line; this indicates a state boundary.

its correct: it's a thin line, and it's a state boundary, correct