M-63 is a state trunkline highway in the US state of Michigan that runs from M-139 at Scottdale through the cities of Benton Harbor and St. Joseph to Interstate 196/US Highway 31 (I-196/US 31) at exit 7 just outside Hagar Shores. The trunkline runs through residential areas south of St. Joseph and through the central business districts of the twin cities. Further north, M-63 runs along the Lake Michigan shoreline. All of M-63's routing was part of US 33 before that highway's truncation south of Niles in 1986. A previous designation of M-63 was used farther north in Lake and Osceola counties from 1919 until 1961. Since the current designation was created, the Michigan Department of Transportation (MDOT) has worked on reconfiguring parts of the roadway in the early part of the 21st century. The bridge M-63 uses to cross the St. Joseph River, the Blossomland Bridge, has been identified as an historic structure using a rare design. The bridge itself dates back to the late 1940s. Route description M-63 begins at the intersection of Niles, Scottdale and Miners roads southwest of St. Joseph in Royalton Township. M-139 runs on Niles Road northwest from Berrien Springs to this point and on Scottdale Road north of the intersection. M-63 follows Miners Road west and then Niles Road northwest of the junction, parallel to the St. Joseph River through residential areas on the outskirts of the twin cities. The highway meets Interstate 94 (I-94) at the latter's exit 27 and continues through St. Joseph Township to the city of St. Joseph. In the city, after Washington Avenue, Niles Road becomes Niles Avenue and turns north. As part of its maintenance duties, the MDOT tracks traffic volumes on the state highways in a metric called average annual daily traffic (AADT), which is a calculation of the average traffic level for any day of a year. The roadway segment along Niles Avenue north of the Napier Avenue intersection in 2009 had the highest traffic levels along all of M-63 at 22,263 vehicles. At Main Street, Niles Avenue ends, and M-63 joins Business Loop I-94 (BL I-94) on Main Street into and through the downtown business district. The two highways continue together running concurrently to Ship and Port streets. These two streets form a one-way pair running east to carry BL I-94 to and from a separate bridge over the St. Joseph River. M-63 continues