It runs north and passes through Little York, then ends at an intersection with SR 250 just before reaching Brownstown.

The much longer northern section starts at I-69 in Martinsville, southwest of Indianapolis, and runs north to the Michigan border near I-94 (via M-239).

Along the route, it passes through these towns (from south to north): 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.