According to the FEIS for the Second Avenue Subway, the IRT Lexington Line carries 1.3 million people a day, more people than all of San Fransisco, Chicago, and Boston's subway systems combined. The Second Avenue Subway is supposed to relieve congestion on the Lexington Avenue Line.
"This is an Raritan Valley express train to Allentown stopping at Newark Penn Station, Westfield, Plainfield, Bridgewater, Somerville, Raritan, High Bridge, Philipsburg, Easton, Bethlehem, and Allentown. Transfer at Newark for service to West Trenton and Lakehurst. Next stop is Newark."