Districts that could tip the house (about 67 races):
AZ: 1, 2, 9
AR: 4
CA: 3, 7, 9, 10, 21, 24, 26, 41, 47, 52
CO: 3, 6
CT: 5
FL: 2, 9, 16, 18, 22, 26
GA: 12
IL: 8, 10, 11, 12, 13, 17
IN: 2
IA: 3, 4
MD: 6
MA: 6
MI: 1, 11
MN: 8
NV: 3, 4
NH: 1, 2
NJ: 3
NY: 1, 11, 18, 19, 21, 24, 25, 27
NC: 7, 8, 11, 13
OH: 6, 16
OK: 2
PA: 8, 12
RI: 1
TX: 23
UT: 4
VA: 2
WA: 1
WI: 7, 8