It is paralleled closely by the incomplete Sanriku Expressway between Sendai and Hachinohe.

National Route 45 has a total length of 516.9 kilometers (321.2 mi).

From there it independently begins heading southeast towards the coastal cities of Hachinohe, Kuji, Miyako, Kamaishi, Kesennuma, and Ishinomaki on the way to its southern terminus in Sendai.

[3] Many sections of the highway along the Sanriku Coast were inundated, destroyed, or swept away by the 2011 Tōhoku earthquake and tsunami event.

It existed from 1953 to 1963, when it was incorporated into the newly formed and longer first-class Route 45.