Baltimore is an important train stop. Amtrak trains in the Northeast Corridor stop in Baltimore. Penn Station is one of the busiest train stations in the country. In 2008 it was the 8th busiest train station in the United States. That year, more than 1 million people took a train to or from Penn Station. Another important train station is at Baltimore-Washington International Thurgood Marshall Airport. Many Amtrak trains stop at the BWI Rail Station. The Amtrak trains that stop in Baltimore are: "Acela Express", "Palmetto", "Carolinian", "Silver Star", "Silver Meteor", "Vermonter", "Crescent", and "Northeast Regional". The MARC commuter rail service also has trains that stop in Baltimore. The MARC trains run from Camden Station and Penn Station in Baltimore to Union Station in Washington, D.C..