Map IN-2 The reversal of the relative positions of /e/ and /ae/ as a measure of the advancement of the Northern Cities Shift.
Map IN-3 The backing of /^/ and the lowering of /oh/ in the Northern Cities Shift.
Map IN-4 The Cartesian distance between /o/ and /oh/ as a measure of the merger.
Map IN-5 The relative fronting and backing of /ay/ and /aw/ in the Inland North and the North Midland.
Map IN-6 The centralization of /ay/ before voiceless obstruents in the Inland North.