The development in the 1850s of hematite iron ore mines in the Upper Peninsula hills above Marquette encouraged the development of numerous railroad plans for spur lines and connecting routes between mines, local boom towns, and the shores of the Great Lakes.
 While most of the Upper Peninsula's iron ore and Keweenaw copper was shipped to the rest of the United States by lake boat, the inability of water-based shippers to offer service to northern Michigan in winter encouraged railroad promoters to launch numerous plans for lines in the Upper Peninsula.

By the 1870s, a maze of corporate charters and tiny stub lines had been created or built in the central Upper Peninsula, primarily to carry iron or copper ore from the mines down to smelters and docks on the shores of Lake Superior and Lake Michigan.
 In 1879-81, venture capitalists led the construction of the Detroit, Mackinac & Marquette (DM&M), a standard-gauge mainline from St. Ignace, on the Straits of Mackinac, to Marquette on Lake Superior.
 The roadbed included a surveyor-straight 25-mile (40 km) east-west section, the ancestor of today's "Seney stretch".
Although the state of Michigan granted the DM&M more than 1.3 million acres (5,300 km²) of state land, almost 9000 acres-per-mile (23 km²/km) as a construction subsidy, by 1886 the new DM&M went into receivership.

The DM&M was reorganized by venture capitalist James McMillan of Detroit, who led the rapid consolidation of the DM&M and many of the UP's smaller railroads during the early 1880s.
 The new Duluth, South Shore & Atlantic went into operation as a merger of these lines in December 1886.
The development in the 1850s of hematite iron ore mines in the Upper Peninsula hills above Marquette encouraged the development of numerous railroad plans for spur lines and connecting routes between mines, local boom towns, and the shores of the Great Lakes.  While most of the Upper Peninsula's iron ore and Keweenaw copper was shipped to the rest of the United States by lake boat, the inability of water-based shippers to offer service to northern Michigan in winter encouraged railroad promoters to launch numerous plans for lines in the Upper Peninsula.
By the 1870s, a maze of corporate charters and tiny stub lines had been created or built in the central Upper Peninsula, primarily to carry iron or copper ore from the mines down to smelters and docks on the shores of Lake Superior and Lake Michigan.  In 1879-81, venture capitalists led the construction of the Detroit, Mackinac & Marquette (DM&M), a standard-gauge mainline from St. Ignace, on the Straits of Mackinac, to Marquette on Lake Superior.  The roadbed included a surveyor-straight 25-mile (40 km) east-west section, the ancestor of today's "Seney stretch". Although the state of Michigan granted the DM&M more than 1.3 million acres (5,300 km²) of state land, almost 9000 acres-per-mile (23 km²/km) as a construction subsidy, by 1886 the new DM&M went into receivership.
The DM&M was reorganized by venture capitalist James McMillan of Detroit, who led the rapid consolidation of the DM&M and many of the UP's smaller railroads during the early 1880s.  The new Duluth, South Shore & Atlantic went into operation as a merger of these lines in December 1886.
Duluth, South Shore and Atlantic Railway