The train as we understand it today consists of a locomotive (though not necessarily) and as many as 150 cars to transport either people or freight. Locomotives in a train system have a number of advantages such as replacement so that the train as a whole can still go on if the engine fails. When locomotives become obsolete the rest of the train system can still be used saving money.
To get faster trains is not what you think. Most trains with current
technology (with slight mods) can go very very fast (>500km/hr). It
is passenger comfort and other issues that keep the trains from going
fast. Here is some things that are done to improve speed.
Railways were actually created in ancient times (Greece and Rome) with stone rail roads for transporting large items such as boats to prevent them from leaving the path. These eventually lead to wood rails and then in the 1700s iron rails. However these railways could not be effectively used for trains.
Locomotives were first developed in 1804 by Richard Trevithick as a steam locomotive.
The first railway lines were laid by Charles Carroll (signer of the Declaration of Independence) in 1828 in Baltimore starting what was known at the Baltimore & Ohio Rail Road (B & O, think Monopoly). The first stone is still on display at the "Birthplace of American Railroading" at the B & O Railroad Museum.
The first trains where pulled by horses, not locomotives in the US because of the sharp curves (locomotives of the time could not take sharp curves).....
Some sites of interest:
EMD -- One of the largest builders of locomotives
Bombardier -- Very large Canadian airplane and train company; builder of the Acela Express (with help from some others including TVG)
Wabtec corporation -- Parts for many transportation systems but mostly locomotives
MotivePower -- A Wabtec company that builds locomotives (The local MARC system has purchased 26 advanced locomotives [MPXpress] from this company)
Baltimore & Ohio Railroad Museum
Trainweb.org -- Hosting service for train systems (lots of small operations)
MARC -- Maryland's local train system
VRE -- Northern Virginia's local train system: cross-over agreement with MARC
MetroRail -- Washington D.C.'s subway rail system
Amtrak -- Rather large railway system in the United States; not the only one though
Amtrak's Acela Express -- Currently the fastest train in the USA (Boston to Washington D.C. in the so-called Northeastern corridor)
Amtrak's Acela Express from Wikipedia
Handbook of Railway Vehicle Dynamics, ed. Simon Iwnicki, CRC Press, New York (2006).
EMD Locomotives, Brain Solomon, Voyageur Press, St. Paul, MN (2006)
Baltimore & Ohio Railroad Museum, http://www.borail.org