This abandoned railway began as part of the Detroit and Lima Northern Railway in 1895, which was built to connect Lima and Toledo, OH, to Detroit, MI. In 1901, it merged with the Ohio Southern Railroad (with roots to 1874) to become the Detroit Southern. The company went bankrupt in 1903, and was reorganized as the Detroit, Toledo and Ironton Railway (DT&I), later Railroad, after another bankruptcy. The company almost went bankrupt again, in 1920, until Henry Ford purchased the railroad.
During Ford's ownership of the DT&I, the company turned around financially, and constructed the Milanta Cutoff in 1925, providing a 55-mile bypass around the cities of Wauseon and Napoleon. The original alignment became the Tecumseh Branch. In 1929, Ford sold the DT&I to the Pennsylvania Railroad (PRR); the PRR merged with the New York Central to become the Penn Central, under which the line was abandoned in two parts, with final abandonment coming in 1978.
Thanks to Aaron M. for contributing information about this route.