In 1947 or early 1948, the Michigan State Highway Department (MSHD) closed the gap between the northern and southern segments of M-65 by adding two "earth" roadways: one between Glennie and M-72 near Curran and a second between Curran and the Alcona–Alpena county line. By the next year, the northern end of the highway near Posen was moved to eliminate several zig-zagging segments of roadway from the routing; M-65 ran due north to terminate at US 23 after the change. In the middle of 1953, the section of M-65/M-72 in Alcona County was straightened and paved. The MSHD realigned M-65 from a series of zig-zagging roads to a single set of curves along the Alcona–Alpena county line in late 1961. At the time this project was completed, all of M-65 was paved.