 When the new alignment for US 27 was opened in early 1949 , M @-@ 18 was re @-@ extended north from Prudenville to Roscommon , where it turned northwesterly with M @-@ 76 to end at US 27 south of Grayling . The completion of two freeways in the state shifted the termini of M @-@ 18 slightly in 1961 . The southern terminus was moved north about a mile ( 1 @.@ 6 km ) to the new US 10 freeway , and the northern terminus was also shifted north about a mile to the new I @-@ 75 / US 27 freeway . The Michigan State Highway Department completed a freeway segment in 1970 in the Roscommon area for the modern I @-@ 75 ; in a temporary assignment they moved M @-@ 18 / M @-@ 76 onto that freeway . When the remainder of the freeway for I @-@ 75 was completed between Roscommon and West Branch in 1973 , M @-@ 18 was rerouted at Roscommon to run northeasterly over the routing of M @-@ 144 , a highway that had existed since 1940 . Part of the former M @-@ 18 / M @-@ 76 routing on the northwestern side of Roscommon was used for BL I @-@ 75 . 
