Originally, based on an incorrect map, the royal charter granted Maryland the Potomac River and territory northward to the fortieth parallel. This was found to be a problem, because the northern boundary would put Philadelphia, the major city in Pennsylvania, within Maryland. The Calvert family, which controlled Maryland, and the Penn family, which controlled Pennsylvania, engaged two surveyors, Charles Mason and Jeremiah Dixon, to survey what became known as the Mason-Dixon line which would form the boundary between their two colonies.
St. Marie's City was the largest site of the original Maryland colony, and was the seat of state government until just before the beginning of the 18th century (when the government was moved to Annapolis). The government was moved at about the same time as the persecution of Maryland Catholics by Puritans from Virginia; during the persecutions, all of the original Catholic churches of southern Maryland were burned down. St Marie's City is now an archaelogical site, with a small tourist center.
Maryland remained largely neutral in the United States Civil War. As it did not secede (in part due to precautions taken by the government in Washington, D.C), it was not included under the Emancipation Proclamation and retained legal slavery for some years after the Civil War.
Maryland's main airport is Baltimore-Washington International Airport (formerly known as Friendship Airport). The Maryland suburbs of Washington, D.C. are also serviced by the other two airports in the region, Reagan National and Dulles International Airports, both in Virginia.
Amtrak Trains serve Baltimore along the Northeast Corridor. MARC trains, operated by the State's Transit Authority, connect nearby Washington, D.C and Baltimore, and other towns.
The state bird is the Baltimore Oriole; the state flower is the black-eyed susan; state sport is jousting; state dog is the Chesapeake Bay Retriever; state fish is the rockfish (striped bass); state cat is the calico cat; and the state song is "Maryland, My Maryland." Nicknames are "The Old Line State" and "The Free State."