Northern section In the 1960s, SR 39 was the connector between the west end of
I-94 (which ended just north of the Michigan-Indiana border) and the
Indiana Toll Road. Hence, a dozen miles of this winding 2-lane road carried all the heavy traffic between Chicago and Detroit. In 2010, the section of SR 39 between Monrovia and
Belleville was greatly improved and re-paved.
Southern section At one point, SR 39 had a section from
US 31 in
Henryville to
SR 3 in
Charlestown. It was later decommissioned when
SR 160 was extended to end in Charlestown. ==Major intersections==