The following sites provide general histories on transportation, engineering and related fields.

http://www.fhwa.dot.gov/infrastructure/history.cfm
Federal Highway Administration history of roads and infrastructure in the United States

http://www.olmsted.org/
National Association for Olmsted Parks, information on Olmsted designed parkways

http://inventors.about.com/library/inventors/bl_history_of_transportation.htm
General transportation history