The New York City Subway, the largest subway system in the world by number of stations, is the primary means of travel within the city, linking every borough except Staten Island. There are 151 subway stations in Manhattan, out of the stations. A second subway, the PATH system, connects six stations in Manhattan to northern New Jersey. Passengers pay fares with pay-per-ride MetroCards, which are valid on all city buses and subways, as well as on PATH trains. There are 7-day and 30-day MetroCards that allow unlimited trips on all subways (except PATH) and MTA bus routes (except for express buses). The PATH QuickCard is being phased out, having been replaced by the SmartLink. The MTA is testing "smart card" payment systems to replace the MetroCard. Commuter rail services operating to and from Manhattan are the Long Island Rail Road (LIRR), which connects Manhattan and other New York City boroughs to Long Island; the Metro-North Railroad, which connects Manhattan to Upstate New York and Southwestern Connecticut; and NJ Transit trains, which run to various points in New Jersey.