Charles Mason (25 April 1728[1] – 25 October 1786) was a British-American astronomer who made significant contributions to 18th-century science and American history, particularly through his survey with Jeremiah Dixon of the Mason–Dixon line, which came to mark the border between Maryland and Pennsylvania (1764–1768).

[2] In 1761, Mason was assigned to travel to the island of Sumatra to observe the transit of Venus as part of an international effort to record data that would enable scientists to determine the distance from the Earth to the Sun.

Owing to an attack by a French man-of-war, they did not reach their destination in time for the transit and were forced to record their observations from the Cape of Good Hope.

In the summer of 1767, the surveying party crossed the Monongahela River and the Great Catawba War Path, violating a treaty limiting the westward expansion of English settlements.

Not wishing to risk inciting native hostilities, Mason and Dixon were forced to return east after making their final observations at the crest of Brown's Hill.

[6] Surveying organizations dedicated a memorial at his previously unmarked grave on 31 August 2013, using a Mason–Dixon line stone that was found displaced from its position.