The Washington Metro is a national treasure.
There are even signs at Metro Center welcoming visitors to "Americas
Subway". Construction on the system ended in 2004 with the system at
full build out (actually about 5 miles more then original plan).
The system is the 2nd busiest subway in
the United States with 5 lines. 8-car trains were introduced in the
mid-2000's, although most trains are 6-cars with a few 4-car trains.
There is continuing talks to add a branch to the orange line to serve
Dulles Airport. There is definite need to add to the system, and
personally I think a M-Street subway connecting Rosslyn, Georgetown,
Dupont Circle and Union Station is a must.
Washington DC, is also interested in
bringing back the streetcars. A line in Anacostia was started, but is
currently on hold
I have only photographed a few
of the 86 station system, so here is just a sampling