Lit.: Three-Province Mountain Pass

During the Sengoku Era, Mikuni Pass was one part of the three-province highway that was the shortest path between Echigo and Edo, but snow drifts and avalanches in winter and landslides in summer made it a difficult crossing. Uesugi Kenshin maintained it during his time as Kantou Kanrei in order to maintain his foothold in the Kantou.

It is now a major artery in the Japanese highway system, designated Highway 17 (Mikuni Tunnel).