Maryland (US: /ˈmɛrɪlənd/ ^ⓘ MERR-il-ənd) is a state in the Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east, as well as with the Atlantic Ocean to its east, and the national capital and federal district of Washington, D.C. to the southwest. With a total area of 12,407 square miles (32,130 km²), Maryland is the ninth-smallest state by land area, and its population of 6,177,224 ranks it the 18th-most populous state and the fifth-most densely populated. Maryland's capital city is Annapolis, and the state's most populous city is Baltimore.

Maryland's coastline was first explored by Europeans in the 16th century. Prior to that, it was inhabited by several Native American tribes, mostly the Algonquian peoples. One of the original Thirteen Colonies, the Province of Maryland was founded in 1634 by George Calvert, 1st Baron Baltimore, a Catholic convert who sought to provide a religious haven for Catholics persecuted in England. In 1632, Charles I of England granted Lord Baltimore a colonial charter, naming the colony after his wife, Henrietta Maria. In 1649, the Maryland General Assembly passed an Act Concerning Religion, which enshrined the principle of toleration. Religious strife was common in Maryland's early years, and Catholics remained a minority, albeit in greater numbers than in any other English colony.

Maryland's early settlements and population centers clustered around waterways that empty into the Chesapeake Bay. Its economy was heavily plantation-based and centered mostly on the cultivation of tobacco. Demand for cheap labor from Maryland colonists led to the importation of numerous indentured servants and enslaved Africans. In 1760, Maryland's current boundaries took form following the settlement of a long-running border dispute with Pennsylvania. Many of its citizens played key political and military roles in the American Revolutionary War. Although it was a slave state, Maryland remained in the Union during the American Civil War, and its proximity to Washington D.C. and Virginia made it a significant strategic location. After the Civil War ended in 1865, Maryland took part in the Industrial Revolution, driven by its seaports, railroad networks, and mass immigration from Europe.

Since the 1940s, the state's population has grown rapidly, to approximately six million residents, and it is among the most densely populated U.S. states. As of 2015^[update], Maryland had the highest median household income of any state, owing in large part to its proximity to Washington, D.C., and a highly diversified economy spanning manufacturing, retail services, public administration, real estate, higher education, information technology, defense contracting, health care, and biotechnology. Maryland is one of the most multicultural states in the country; it is one of the nine states where non-Whites compose a majority of the population, with the fifth-highest percentage of African Americans, and high numbers of residents born in Africa, Asia, Central America, and the Caribbean. The state's central role in U.S. history is reflected by its hosting of some of the highest numbers of historic landmarks per capita.

The western portion of the state contains stretches of the Appalachian Mountains, the central portion is primarily composed of the Piedmont, and the eastern side of the state makes up a significant portion of the Chesapeake Bay. Sixteen of Maryland's twenty-three counties, and the city of Baltimore, border the tidal waters of the Chesapeake Bay estuary and its many tributaries, which combined total more than 4,000 miles of shoreline. Although one of the smallest states in the U.S., it features a variety of climates and topographical features that have earned it the moniker of America in Miniature. Maryland's geography, culture, and history are diverse, including elements of the Mid-Atlantic, Northeastern, and Southern regions of the country.

Present-day Maryland was originally inhabited by tribes such as the Piscataway (including the Patuxent), the Nanticoke (including the Tocwogh, the Ozinie and other subdivisions), the Powhatan, the Lenape, the Susquehannock, the Shawnee, the Tutelo, the Saponi, the Pocomoke and the Massawomeck.^{[self-published source?]} George Calvert, 1st Baron Baltimore (1579–1632), sought a charter from King Charles I for the territory between Massachusetts to the north and Virginia to the immediate south. After Baltimore died in April 1632, the charter was granted to his son, Cecilius Calvert, 2nd Baron Baltimore (1605–1675), on June 20, 1632. Officially, the new "Maryland Colony" was named in honor of Henrietta Maria of France, wife of Charles I. Lord Baltimore initially proposed the name "Crescentia", the land of growth or increase, but "the King proposed Terra Mariae [Mary Land], which was concluded on and inserted in the bill."

The original capital of Maryland was St. Mary's City, on the north shore of the Potomac River, and the county surrounding it was the first erected and created in the province, first called Augusta Carolina, after the King, and later named St. Mary's County.

Lord Baltimore's first settlers arrived in the new colony in March 1634, with his younger brother, Leonard Calvert (1606–1647), as the first provincial Governor of Maryland. They made their first permanent settlement at St. Mary's City in what is now St. Mary's County. They purchased the site from the paramount chief of the region, who was eager to establish trade. St. Mary's became the first capital of Maryland, and remained so for 60 years until 1695. More settlers soon followed. Their tobacco crops were successful and quickly made the new colony profitable. However, given the incidence of malaria, yellow fever, and typhoid, life expectancy in Maryland was about 10 years less than in New England.