1793 – Mason and Dixon arrive in Philadelphia

Charles Mason and Jeremiah Dixon were a pair of English astronomers who were hired by Thomas Penn and Frederick Calvert, respectively the proprietors of Pennsylvania and Maryland, to resolve a boundary dispute between the two colonies in 1763. The two had worked together for two years before that, Dixon serving as Mason’s assistant.

The survey took three years to complete – and the pair remained in America for another two years after that, being admitted to the American Society for Promoting Useful Knowledge, in 1768, before they left American in the same way they had entered it: via Philadelphia.

Referenced in:

Sailing To Philadelphia — Mark Knopfler

1767 – Mason and Dixon complete the surveying of the Line between Maryland and Pennsylvania

Charles Mason, a fellow of the Royal Society and noted astronomer, and his sometime assistant, land surveyor and amateur astronomer, Jeremiah Dixon, were hired by certain wealthy interests in what was then the British colony of America to conclude a number of difficult boundary disputes in the young colonies.

Landing in Philedelphia in 1763, Mason and Dixon spent the next four years painstakingly measuring and fixing the proper boundaries between the various colonies, ceasing their work on October 18, 1867. (A team of their subordinates completed the survey in 1787.)

The lines they laid down, although resurveyed since that time, formed the basic lines of the borders between the colonies (and later the states) of Delaware, Maryland, Pennsylvania and West Virginia. Later, as these states took different sides in the Civil War, the line came to symbolise the political and cultural border between the southern and northern states.

Referenced in:

Sailing To Philadelphia – Mark Knopfler

It is also possible that Dixon’s name is the origin of the south’s nickname of “Dixie”.