Born in Lancaster County on 13 Apr. 1711, John Mitchell studied medicine at the University of Edinburgh and in 1734 opened a practice here in Urbanna. In 1746, he moved to London, where he published his Map of the British and French Dominions in North America in 1755. British and American diplomats used the map, acclaimed for its accuracy, to negotiate the Treaty of Paris in 1783, which ended the Revolutionary War and established boundaries for the new nation. The map served to document treaties into the 20th century. Mitchell died in or near London on 29 Feb. 1768.