The Detroit and Mackinac Railway, informally known as the "Turtle Line", was a railroad in the northeastern part of the Lower Peninsula of the U.S. state of Michigan. The railroad had its main offices and shops in Tawas City with its main line running from Bay City north to Cheboygan, and operated from 1894 to 1992. In 1946, it became the first all diesel haul railroad in the United States.

Alpena is a city in the U.S. state of Michigan. It is the county seat of Alpena County, and is the only city within the county. The population was 10,197 at the 2020 census, making it the third most populated city in the Northern Michigan region, after Traverse City and Cadillac. The city is surrounded by Alpena Township, but the two are administered autonomously. It is the core city of the Alpena micropolitan statistical area, which encompasses all of Alpena County and had a total population of 28,907 at the 2020 census.