February 10:  The Lake Superior iron region produces its first iron.  They did not ship iron "ore" until later.  [MSL]

May 30:  New Michigan Central depot west of Third Street near the river, opens in Detroit.  [DWS/AAD]

December 1:  Michigan Central Railroad reaches Niles.   [MCR-75/ IT-12/79/AAD]  Also noted as being October 1, 1848 by [MT]  [MCR-75] dates this as "Autumn, 1848"

The Erie and Kalamazoo is purchased by out-of-state interests and changed to standard gauge.  It had been 4' 10" gauge.  [AAD]

The Illinois and Michigan Canal opens from Chicago to the Mississippi River.  The opening creates a large demand for pine lumber from Michigan.  [MH-11/1993]

The Michigan Central Railroad removed its line in Detroit along Michigan Avenue to Woodward, after the passenger depot was changed to the foot of Third Street.  [HWC]

Schenecectday Locomotive Works is founded.  They create their first engine, "Lightening".  [SAM]