Staten Island,
New York's lone train line. Runs the entire length of the borough from the
Staten Island Ferry terminal in the north to the southern tip in Tottenville, a total distance of 14 miles. There are 22 stops on the route.
The line has direct connections to the ferry. The cost is $1.50, same as a New York City subway. In fact, one can pay for SIRT with a Metrocard and get a free transfer to the subway in Manhattan. This allows one to go from the southern end of Staten Island all the way to the northern part of the Bronx (a journey that would take around 2 hours) for just $1.50.
The fare is paid only at the ferry terminal, so if one traveled using the SIRT and did not start at or end up at the ferry, the ride is free.
SIRT runs along the eastern shore of Staten Island, thus not in walking distance of everyone in the borough. Trains are 4 cars long (sometimes 2 in off-hours and weekends).
SIRT is usually on-time and one can often get a seat, except during rush hour. Trains run 24 hours on a set schedule, with more trains during rush hours and less at night. All trains make all stops, except for some express schedules during rush hours.
www.nycsubway.org/us/sirt describes SIRT in much more detail.