Key highway systems by country:
I-10, I-20, I-30, I-40, I-50, I-60, I-70, I-80, I-90
Trans-Canada Highway, Hwy 401, Hwy 17, Hwy 1, Hwy 11, Hwy 16, Hwy 417
M1, M25, M3, M4, M5, M6, M8
BAB 1, BAB 2, BAB 3, BAB 4, BAB 5, BAB 6, BAB 7
G1 Beijing–Harbin, G2 Beijing–Shanghai, G3 Beijing–Taipei, G4 Beijing–Hong Kong–Macau, G5 Beijing–Kunming, G6 Beijing–Lhasa, G7 Beijing–Urumqi