These were the road that ran from Shirakawa City in Mutsu Province to Sendai City and the one that ran from Sendai through Matsumae-cho (Hokkaido) to Hakodate City, and the most part of Route 4 covers the route of them.
陸奥国白河市から仙台市までと、仙台から松前町(北海道)を経て函館市に至る街道で、国道4号をほぼなぞる。