In 1926, the affiliated Shore Line Motor Coach Co. acquired from B. P. Shearon's Bus Line, a route between Michigan City and Benton Harbor, Michigan. The bus route would a form connection with the trains at Michigan City. East of Michigan City the route would operate via Dunes Hwy (US 12) (PSCI Certificate 557M).
Shore Line Motor Coach Co. also acquired and introduced additional bus routes operating into Michigan. One of the earliest bus routes authorized to serve Michigan City was in 1925, operated by Joseph C. Rachor east of Michigan City into Michigan vis Lake Shore Dr., later B. P. Shearon's Bus Line (PSCI Certificate 106M).
In 1927, when Shore Line Motor Coach Co. sold its Michigan routes to a predecessor of Greyhound, the South Shore Line assumed direct operation of the Benton Harbor bus service. Bus service continued until 1963.
In 1927, Shore Line Motor Coach Co. introduced a new luxury "Golden Arrow" bus route between South Bend and Detroit, connecting with the trains in South Bend.
Another bus company acquired by Shore Line Motor Coach Co. in 1927 was Carey & Leach Bus Lines, operating between Chicago and Detroit via Kalamazoo, Michigan. In 1927, Shore Line Motor Coach Co. sold its routes east of Michigan City to Southwestern Michigan Motor Coach Co., which the following year would be sold to Motor Transit Corp., a predecessor of Greyhound.