M-39 is a 16-mile-long (26 km) north–south state trunkline highway in Metro Detroit area of the US state of Michigan that runs from Lincoln Park, on the south end, to Southfield on the north. The official southern terminus of M-39 is at the corner of Southfield Road and Lafayette Boulevard in Lincoln Park, one block southeast of the junction of Interstate 75 (I-75, Fisher Freeway) and two blocks northwest of M-85 (Fort Street). From there the highway heads northward. The first 2.3 miles (3.7 km) of the highway follows Southfield Road, a divided highway in the Downriver area. It then transitions into the Southfield Freeway, which is a 13.7-mile-long (22.0 km) freeway that runs from Allen Park north through Dearborn, and then the west side of Detroit, to Southfield. The northern terminus is at M-10 (Lodge Freeway) in Southfield. The current M-39 is the third highway to bear the designation. The first dated back to the origins of the state highway system in 1919 and ran between Grand Rapids and Lansing. This highway was replaced in segments through the 1920s and 1930s by realignments or extensions of other highways in the area. The second was part of Schaefer Highway in the Detroit area from 1939 until the end of the 1950s. The current highway was commissioned when the M-39 designation was moved to Southfield Road from Schaefer Highway. During the 1960s, it was converted into a freeway in stages. Afterwards, it was extended to end at M-85 (Fort Street) before a change in the 1980s gave the trunkline its present termini. From Wikipedia
