Porter Subdivision

The Porter Subdivision is a railroad line owned by CSX Transportation in the Chicago, Illinois area. Formerly a part of the main line of the Michigan Central Railroad, it now connects CSX's former Baltimore and Ohio Railroad line and the Chicago Fort Wayne and Eastern Railroad from the east with the Indiana Harbor Belt Railroad towards Blue Island, Illinois.

The Michigan Central Railroad built a line from Detroit, Michigan to Chicago, Illinois, opening in mid-1852, several months after the competing Northern Indiana and Chicago Railroad (later the New York Central Railroad's main line) was completed. The MC's path entered Indiana near Michigan City, crossing the NI&C at Porter. From Porter it looped to the southwest and northwest, joining the Illinois Central Railroad at Kensington, Illinois south of Chicago. Later the Michigan Central (and the Northern Indiana and Chicago's successor, the Lake Shore and Michigan Southern Railway) came under control of the New York Central.

Eventually the NYC started to operate most trains west from Porter via the LS&MS, and the MC became a secondary route. All passenger trains moved on January 18, 1957, ending service to local stations in Gary and Hammond. In 1964 the NYC merged into Penn Central Transportation, and into Conrail in 1976. Around then the diamonds were removed at Porter, physically separating the line to Detroit from the line to Kensington, which came to be known as the Porter Branch. After 1980 Amtrak bought the line from Porter to Michigan City, Indiana, east of which they already owned to Kalamazoo, Michigan, about 2/5 the way to Detroit.

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