M-28 is an east–west state trunkline highway that traverses nearly all of the Upper Peninsula of the U.S. state of Michigan, from Wakefield to near Sault Ste. Marie in Bruce Township. Along with US Highway 2 (US 2), M-28 forms a pair of primary highways linking the Upper Peninsula from end to end, providing a major access route for traffic from Michigan and Canada along the southern shore of Lake Superior. M-28 is the longest state trunkline in Michigan numbered with the "M-" prefix at 290.373 miles (467.310 km). The entire highway is listed on the National Highway System, while three sections of M-28 are part of the Lake Superior Circle Tour. M-28 also carries two memorial highway designations along its route.

Throughout its course across the Upper Peninsula, M-28 passes through forested woodlands, bog swamps, urbanized areas, and along the Lake Superior shoreline. Sections of roadway cross the Ottawa National Forest and both units of the Hiawatha National Forest. Some of the other landmarks accessible from M-28 include the Seney Stretch, Seney National Wildlife Refuge and several historic bridges.

M-28 is an original trunkline designation, dating to the 1919 formation of the state's trunkline system. The original highway was much shorter than the current version. M-28 was expanded eastward to the Sault Ste. Marie area in the late 1920s. The western end has been expanded twice to different locations on the Wisconsin state line. Other changes along the routing have led to the creation of three different business loops at various times, with one still extant. Future changes, proposed by Marquette County but not accepted by the Michigan Department of Transportation (MDOT), could see M-28 rerouted over County Road 480 (CR 480).

M-28 is a major highway for Michigan and Canadian traffic along the south shore of Lake Superior. It forms the northern half of a pair of primary trunklines linking the Upper Peninsula from end to end; US 2 is the southern partner. The 290.373-mile (467.310 km) highway comprises mostly two lanes, undivided except for sections that are concurrent with US 41 near Marquette. The "Marquette Bypass" portion of US 41/M-28 is a four-lane expressway, and segments of the highway in Marquette County have four lanes. The entire route is part of the National Highway System, and three sections of the trunkline are part of the Lake Superior Circle Tour.

In the west, M-28 begins at a signalized intersection with US 2 in Wakefield. Heading north, the highway passes Sunday Lake heading out of town. After crossing into southwestern Ontonagon County and the Eastern Time Zone, the trunkline highway skirts the northern shore of Lake Gogebic, running concurrently with M-64. The first section of M-28 designated as a part of the Lake Superior Circle Tour is from the western terminus to the eastern junction with M-64 in Bergland, where the Circle Tour turns north along M-64, leaving M-28. Here, M-28 has its lowest traffic counts; within the 2013 MDOT survey, the road is listed with only an average annual daily traffic (AADT) of 1,425 vehicles on a section of highway between Bergland and the US 45 intersection in Bruce Crossing. The trunkline runs through heavily forested areas of southern Houghton and Baraga counties. At the eastern junction with US 41 near Covington, M-28 receives the Circle Tour designation again and exits the Ottawa National Forest.

In Baraga and Marquette counties, US 41/M-28 passes through hilly terrain before entering the urban areas of Ishpeming, Negaunee and Marquette. Approximately 13,000–17,000 vehicles use this section from Ishpeming eastward through Negaunee. West of the city of Marquette, US 41/M-28 had a peak 2013 AADT of 32,805 vehicles in Marquette Township along a retail and business corridor. This peak level is sustained until the start of the Marquette Bypass, where the traffic returns to the 16,500-vehicle and higher levels seen in Ishpeming and Negaunee. South of the city of Marquette, traffic counts once again climb to 19,620 vehicles. In Chocolay Township the AADT drops to 8,840 vehicles before tapering off to 3,065 vehicles by the county line.

At the Ishpeming–Negaunee city line, M-28 changes memorial highway designations. From the western terminus to this point, M-28 is called the "Veterans Memorial Highway", but it becomes the "D. J. Jacobetti Memorial Highway" to honor the longest-serving member of the Michigan Legislature, Dominic J. Jacobetti. The Jacobetti Highway designation ends at the eastern M-123 junction in Chippewa County.

Between Marquette and Munising, M-28 closely parallels the Lake Superior shoreline, providing scenic views of the lake and its "lonesome sandy beaches". The Lakenenland sculpture park is located in Chocolay Township near Shot Point in eastern Marquette County. This roadside attraction is owned by Tom Lakenen and features fanciful works of art made of scrap iron. Near the community of Au Train, M-28 crosses into the western unit of the Hiawatha National Forest. West of Munising is a ferry dock offering transport to the Grand Island National Recreation Area, and at Munising there is easy access to Pictured Rocks National Lakeshore. The roadway also features variable-message signs to warn motorists of winter weather-related traffic closures along the lakeshore. Installed at the US 41 and M-94 junctions, the signs advise motorists which sections of roadway are closed. Per MDOT policy, only snowplows are allowed on these sections during a closure. The highway exits the Hiawatha National Forest at the Alger County–Schoolcraft County line along the Seney Stretch.