In June, the Harrisburg, Pa.-to-Philadelphia-to-New York City line carried 72,091 passengers, a 20 percent increase compared with June 2005.

And through June, fiscal-year 2006 Keystone ridership totaled 615,124 passengers, up 13 percent compared with the same FY2005 period.

Amtrak officials attribute the increase to a $145 million track improvement project under way on the line. The national intercity passenger railroad and commonwealth of Pennsylvania are jointly funding the project, which includes installing ties, switches and a new signal system, and upgrading bridges and culverts, overhead electrical wires and electrical substations.

Scheduled to be complete in fall, the project is designed to increase train speeds, improve ride quality, and enable Amtrak to operate more frequent service between Philadelphia, Lancaster and Harrisburg, Pa.