Amtrak's "Acela Express", "Northeast Regional", and long distance trains share tracks along the whole of the Penn Line. Washington Union and Baltimore Penn are the second and eighth busiest Amtrak stations in the country, respectively. Amtrak connections are also available at , and . MARC passengers with monthly and weekly tickets can ride select Amtrak "Northeast Regional" trains during the week only, as part of their cross-honoring agreement. Connections are also available to the Washington Metro's Orange Line at New Carrollton, Red Line at Washington Union Station, and to the MTA Light Rail at Baltimore Penn Station.