Editing Maryland (section)

===Border disputes (1681–1760)===
{{Main|Penn–Calvert boundary dispute|Cresap's War}}
[[File:1732 map of Maryland.jpg|thumb|A 1732 map of Maryland<ref>{{Cite web|url=https://ghostsofbaltimore.org/2014/03/04/lord-baltimores-map-maryland-1732/|title=Lord Baltimore's Map of Maryland in 1732|last=Tom|date=March 4, 2014|website=Ghosts of Baltimore|access-date=February 24, 2019|archive-date=February 25, 2019|archive-url=https://web.archive.org/web/20190225044819/https://ghostsofbaltimore.org/2014/03/04/lord-baltimores-map-maryland-1732/|url-status=live}}</ref>]]
The royal charter granted Maryland the land north of the [[Potomac River]] up to the [[40th parallel north|40th parallel]]. A problem arose when [[Charles II of England|Charles II]] granted a charter for the [[Province of Pennsylvania]], which defined Pennsylvania's southern border as the 40th parallel, identical to Maryland's northern border. But the grant indicated that Charles II and [[William Penn]] assumed the 40th parallel would pass close to [[New Castle, Delaware]], where it falls north of [[Philadelphia]], which Penn already designated as Pennsylvania's capital city. Negotiations ensued after the problem was discovered in 1681.

A compromise proposed by Charles II in 1682 was undermined by Penn's receiving the additional grant of what is now Delaware.<ref name=hubbard>{{Cite book|last=Hubbard |first=Bill Jr. |title=American Boundaries: the Nation, the States, the Rectangular Survey |url=https://archive.org/details/americanboundari00jrbi |url-access=limited |year=2009 |publisher=University of Chicago Press |isbn=978-0-226-35591-7 |pages=[https://archive.org/details/americanboundari00jrbi/page/n35 21]–23}}</ref> Penn successfully argued that the Maryland charter entitled Lord Baltimore only to unsettled lands, and Dutch settlement in Delaware predated his charter. The dispute remained unresolved for nearly a century, carried on by the descendants of William Penn and Lord Baltimore—the [[Baron Baltimore|Calvert family]], which controlled Maryland, and the [[William Penn|Penn family]], which controlled Pennsylvania.<ref name=hubbard/>

The border dispute with Pennsylvania led to Cresap's War in the 1730s. Hostilities erupted in 1730 and escalated through the first half of the decade, culminating in the deployment of military forces by Maryland in 1736 and by Pennsylvania in 1737. The armed phase of the conflict ended in May 1738 with the intervention of King George II, who compelled the negotiation of a cease-fire. A provisional agreement had been established in 1732.<ref name=hubbard/>

Negotiations continued until a final agreement was signed in 1760. The agreement defined the border between Maryland and Pennsylvania as the line of latitude now known as the [[Mason–Dixon line]]. Maryland's border with Delaware was based on the [[Transpeninsular Line]] and the [[Twelve-Mile Circle]] around New Castle.<ref name=hubbard/>