M-24 is a north–south state trunkline highway in the U.S. state of Michigan that extends through Southeast Michigan and The Thumb, from northeast Auburn Hills to Unionville. It starts at an interchange with Interstate 75 (I-75) and ends where it merges with M-25. While the M-24 designation is similar to that of US Highway 24 (US 24) which has a northern terminus located only a few miles from the southern terminus of M-24, M-24 was never part of US 24. The first M-24 in Michigan was replaced by M-20 when US 10 replaced the original M-20 in 1926. A 1936 bypass of downtown Pontiac resulted in the creation of M-24A which later became BUS M-24 in 1940. An extension in 1997 moved the northern end of M-24 northward from Caro to Unionville, replacing a section of M-138 in the process. Route description M-24 begins a hundred feet south of an overpass that is part of a double trumpet interchange with I-75 in Auburn Hills. The interchange also connects with an entrance into The Palace of Auburn Hills, former home of the NBA's Detroit Pistons, and a variety of electronic signs are contained in the area to indicate the status of access to the entrance. The roadway is a continuation of Business Loop I-75 (BL I-75) that travels through Pontiac. This section of the highway dedicated to William Davidson, former owner of the Pistons, in legislation signed by Michigan Governor Rick Snyder in May 2011. The section of M-24 from its southern terminus in Auburn Hills north to the village of Oxford is one of the busiest stretches of road in the state in terms of annual average daily traffic (AADT). Near The Palace of Auburn Hills, 50,600 vehicles used the roadway on average in 2007. The road is a standard Michigan expressway design, with at-grade intersections, traffic signals, and Michigan Lefts. M-24 continues north through the Bald Mountain Recreation Area and along the eastern shore of Lake Orion in the village of Lake Orion. This expressway continues a few miles north of the Lapeer County line, where the highway becomes a two-lane highway for a few miles, before returning to expressway from Metamora to I-69. South of Metamora, M-24 runs parallel to the former right-of-way for the Michigan Central Railroad north into the city of Lapeer. M-24 continues north from Lapeer running west of Barnes Lake and east of the