George Calvert, 1st Baron Baltimore in the context of "William Claiborne"

Maryland (US: /ˈmɛrɪlənd/ MERR-il-ənd) is a state in the Mid-Atlantic and South 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 km), 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.

Protestantism is the largest grouping of Christians in the United States, with its combined denominations collectively comprising about 43% of the country's population (or 141 million people) in 2019. Other estimates suggest that 48.5% of the U.S. population (or 157 million people) is Protestant. Simultaneously, this corresponds to around 20% of the world's total Protestant population. The U.S. contains the largest Protestant population of any country in the world. Baptists comprise about one-third of American Protestants. The Southern Baptist Convention is the largest single Protestant denomination in the U.S., comprising one-tenth of American Protestants. Twelve of the original Thirteen Colonies were Protestant, with only Maryland having a sizable Catholic population due to Lord Baltimore's religious tolerance.

The country's history is often traced back to the Pilgrim Fathers whose Brownist beliefs motivated their move from England to the New World. These English Dissenters, who also happened to be Puritans—and therefore Calvinists—, were first to settle in what was to become the Plymouth Colony. America's Calvinist heritage is often underlined by various experts, researchers and authors, prompting some to declare that the United States was "founded on Calvinism", while also underlining its exceptional foundation as a Protestant majority nation. American Protestantism has been diverse from the very beginning with large numbers of early immigrants being Anglican, various Reformed, Lutheran, and Anabaptist. In the next centuries, it diversified even more with the Great Awakenings throughout the country.

There are 23 counties and one independent city in the U.S. state of Maryland. Many of the counties in Maryland were named for relatives of the Barons Baltimore, who were the proprietors of the Maryland colony from its founding in 1634 through 1771. The Barons Baltimore were Catholic, and George Calvert, 1st Baron Baltimore, originally intended that the colony be a haven for English Catholics, though for most of its history Maryland has had a majority of Protestants.

Though formally an independent city rather than a county, the City of Baltimore is considered the equal of a county for most purposes and is functionally a county-equivalent in most respects.

Cecil Calvert, 2nd Baron Baltimore (8 August 1605 – 30 November 1675) was an English politician and lawyer who was the first proprietor of Maryland. Born in Kent, England in 1605, he inherited the proprietorship of overseas colonies in Avalon (Newfoundland) along with Maryland after the 1632 death of his father, George Calvert, 1st Baron Baltimore (1580–1632), for whom it had been originally intended in a vast land grant from King Charles I (1600–1649, reigned 1625–1649). Young Calvert proceeded to establish and manage the Province of Maryland as a proprietary colony for English Catholics from his English country house of Kiplin Hall in North Yorkshire.

As a Catholic, he continued his father's legacy by promoting religious tolerance in the colony. He also was involved in the establishment of the Newfoundland Colony and the Province of Avalon. Maryland quickly became a haven for English Catholics in the Americas, particularly due to rising religious persecution in England. Governing Maryland's affairs since its founding for 44 years, Calvert died in England in 1675. After his death, the Protestant Revolution along the Chesapeake Bay ("Glorious Revolution") of 1689, matched events occurring overseas across the Atlantic Ocean in Europe, overturning King James II and the Stuart royal dynasty of England and Scotland, and ended Roman Catholic control (and temporarily that of the Calvert family and the Lords Baltimore) of the Province of Maryland colony (including the other original Thirteen Colonies along the East Coast of British America), and established Protestant supremacy.

Leonard Calvert (c. 1606 – 9 June 1647) was an English-born colonial administrator who served as the first proprietary governor of Maryland from 1634 to 1647. He was the second son of George Calvert, 1st Baron Baltimore, the first lord proprietor of the Province of Maryland. His elder brother Cecil, who inherited the colony and the title upon the death of their father in 1632, appointed Leonard as governor of Maryland in his absence.