The Michigan Air Line Railroad was a planned railroad across southern Michigan, connecting the Canada Southern Railway to Chicago, Illinois. Only part of the line was built, and it was split between the Michigan Central Railroad (part of the New York Central Railroad, which also acquired the Canada Southern Railway) and the Grand Trunk Railway.
The Grand Trunk Railway was chartered in Michigan and Indiana, and the two companies merged in July and August 1868, just after the Canada Southern Railway was chartered, to form the Michigan Air Line Railroad. The Michigan Air Line and Canada Southern planned to form a continuous line from Buffalo, New York west to Chicago, Illinois via a train ferry across the St. Clair River. In 1871 the line was planned as part of a longer Portland, Rutland, Oswego and Chicago Railroad, but that fell through.
On October 11, 1870 the St. Joseph Valley Railroad was merged into the company, providing a branch from Niles south to South Bend, Indiana. That line had opened in Spring 1870.
The main line was completed February 1871 from Niles east to Jackson and from Romeo east to Richmond, and was leased to the Michigan Central Railroad (as part of a shorter route between Detroit and Chicago). The Michigan Midland and Canada Railway was chartered in 1872 to continue east from Richmond to the St. Clair River, and opened in 1873 as part of the Canada Southern Railway. However, due to financial problems, the part between Jackson and Romeo was not built.
The east part, from Romeo to Richmond, was split off on October 2, 1872 as the St. Clair and Chicago Air Line Railroad, which leased the unbuilt St. Clair River, Pontiac and Jackson Railroad. The company went bankrupt in 1873, and on November 18, 1875 it was sold at foreclosure, with those lines east of Pontiac sold to the Michigan Air Line Railway. That company made arrangements for operation by the Grand Trunk Railway (which passed through Richmond). On January 1, 1881, the Grand Trunk leased the company, and the line was finished west to Jackson on September 1, 1884. The line from Pontiac to South Lyon was built on the planned right-of-way of the Toledo, Ann Arbor and North Eastern Railroad.
In 1916 the Michigan Air Line Railroad merged with the Michigan Central and ceased to exist as an independent company; the Michigan Air Line Railway merged with the Grand Trunk Western in 1928.
In 1984, Grand Trunk Western sells an 8-mile stretch of track between Wixom (CSX line) and West Bloomfield in Oakland County to Coe Rail, Inc. It operates the Michigan Star Clipper Dinner Train and a small freight operation.
In 2006, Coe Rail Inc. is acquired by Railmark Holdings. In 2007, it renames the line back to its original namesake, Michigan Air-Line Railway. The last excursion of the Michigan Star Clipper Dinner Train was made on December 31, 2008.
On November 12, 2009, Railmark sold the Michigan Air-Line Railway to the Nebraska-based Browner Turnout Company. On January 28, 2011, Michigan Air-Line Railway applied to abandon its route. The railroad was removed between Walled Lake and the interchange in Wixom in Spring of 2012. This left the entire Michigan Air Line Railroad abandoned.
As of 2015, sections of the rail grade have been (and continue to be) converted into a rail trail known as the Michigan Air Line Trail.