 When the highway was first designated in the late 1910s , it extended farther south than it does today and ended well short of its current northern terminus . The southern end was added to another state highway , truncating M @-@ 18 's length to roughly its current southern terminus in 1926 . The northern end was also simultaneously extended for the first time with these revisions to the highway 's routing . In the 1940s , the northern extension was reversed and then reinstated . M @-@ 18 's course was last changed with the opening of three different freeways in the area in the 1960s and 1970s . The last extension in 1973 supplanted the M @-@ 144 designation from Roscommon north to Luzerne . 
