The Northern Indiana Railroad Company, not to be confused with a later company of the same name, began with a charter for The Buffalo and Mississippi Railroad Company. The BMR Company was chartered to run from the navigable water at the west end of Lake Erie (head of Maumee Bay) to the navigable water below the rapids of the Illinois River (Ottawa, Illinois). In 1837 the Indiana Legislature amended the original act, renaming the company Northern Indiana Railroad Company.
In 1846, the line west of Laporte changed to a direction toward Chicago. I assume it was originally planned for Ottawa. The grading that had been done was not used as it was too steep,
Reported in the 25 July 1850 State Indiana Sentinel: June 11th of 1850 the Governor of Indiana officially recognized the Northern Indiana Railroad Company.
By 1851 Northern Indiana had completed a length between South Bend and White Pigeon and joined with the Michigan Southern Railway. The choice of White Pigeon may have been related to a situation faced by the Michigan Southern. Due to lobbying by the Michigan Central Railroad, a competitor of the Michigan Southern, the latter's charter prevented it from going within two miles of the Indiana state line east of Constantine. However the most practical route went closer than two miles west of White Pigeon. To allow for this, Judge Stanfield of South Bend, IN bought the right-of-way from White Pigeon to the state line, and leased it to the railroad company for about 10 years until the charter was modified to allow the company to own it.
June 13, 1853, Northern Indiana Railroad merged with an Ohio company of the same name in anticipation of a road east from Goshen to Toledo. They had already run a line from Elkhart to Goshen in 1852.
April 25, 1855: NI merged with Michigan Southern to form the Michigan Southern & Northern Indiana Railroad Company.
April 6, 1869: MS&NI merged with the Lake Shore railroad to form the Lake Shore & Michigan Southern Railroad.