A Pure Michigan Byway is the designation for a segment of the State Trunkline Highway System in the US state of Michigan that is a "scenic, recreational, or historic route that is representative of Michigan's natural and cultural heritage." The designation was created with the name Michigan Heritage Route by the state legislature on June 22, 1993, and since then six historic, seven recreational and seven scenic byways have been designated by the Michigan Department of Transportation (MDOT), and another two have been proposed. These byways have been designated in both the Upper and Lower peninsulas of the state. The current name was adopted on December 30, 2014, and it references the Pure Michigan tourism marketing campaign.

The State Trunkline Highway System consists of all the state highways in Michigan, including those designated as Interstate, United States Numbered, or State Trunkline highways. In their abbreviated format, these classifications are applied to highway numbers with an I-, US, or M- prefix, respectively. The system is maintained by the Michigan Department of Transportation (MDOT) and comprises 9,669 miles (15,561 km) of trunklines in all 83 counties of the state on both the Upper and Lower peninsulas, which are linked by the Mackinac Bridge. Components of the system range in scale from 10-lane urban freeways with local-express lanes to two-lane rural undivided highways to a non-motorized highway on Mackinac Island where cars are forbidden. The longest highway is nearly 400 miles (640 km) long, while the shortest is about three-quarters of a mile. Some roads are unsigned highways, lacking signage to indicate their maintenance by MDOT; these may be remnants of highways that are still under state control whose designations were decommissioned or roadway segments left over from realignment projects.