M-37 through the south side of the Grand Rapids area was realigned in late 1949 or early 1950. After the change, the highway follows Broadmoor Avenue to 28th Street and 28th Street west to its former routing along Kalamazoo Avenue. In 1953, this routing was shifted further when M-37 was rerouted to run north on East Beltline Avenue concurrent with US 131 and M-21 to Cascade Road. There it turned west along Cascade Road and Fulton Street into downtown back to its existing alignment. During that same time frame, the gap in the routing between M-55 and Mesick was eliminated. The highway was moved to bypass Sparta, Kent City and Casnovia to the southwest in the 1962. Another change around the same time frame shifted M-37's routing through Grand Rapids again. This time, M-37 was rerouted to follow M-11/M-21 along 28th Street to the US 131 freeway north to I-96 and back to Alpine Avenue. The final Grand Rapids routing change was made in 1969 when M-37 was moved to its current course along East Beltline Avenue and I-96. This change resulted in a concurrency with the southernmost end of M-44 that was later removed in 1977 when M-44 was truncated northward. A proposed new routing near Comstock Park in the 1970s would have removed M-37 from Alpine Avenue. The new highway, if built, would have run southeastward from the Alpine Avenue split to US 131 near 6 Mile Road. In 2008, the northernmost on the Old Mission Peninsula were designated what is now a Pure Michigan Scenic Byway by MDOT. In 2013, the hairpin curve on a hill north of Mesick was straightened and the hill slightly leveled.