| Y/M/D | Description | Place |
|---|---|---|
| 1763/07/20 | Astronomer Charles Mason and surveyor Jeremiah Dixon are hired and paid 3,512 pounds, or about $840,000 in 2017, adjusted for inflation. | Delaware Boundary Markers, Delaware |
| 1763/11/00 | Charles Mason and Jeremiah Dixon survey the first degree of latitude in America, near where South St meets Front St in Philadelphia. | Old City, Philly, |
| 1765/04/00 | Mason and Dixon begin their survey of the Maryland-Pennsylvania border. | |
| 1765/06/00 | While surveying the area, Mason and Dixon used Newark as their base of operation, staying at St Patricks Inn, the precursor to the Deer Park Tavern. | |
| 1765/06/06 | Charles Mason and Jeremiah Dixon stop about 4 miles northwest of Newark and drive a wooden post into the ground establishing the dividing point between Delaware, Maryland and Pennsylvania. | Tri-State Mason Dixon Marker, McClellandville, DE |
| 1784/00/00 | David Rittenhouse, surveyor Andrew Ellicott and their crew complete the Mason-Dixon line survey at the southwest corner of Pennsylvania, 5 degrees of longitude from the Delaware River. | |
| 1849/11/15 | In consequence of the accidental removal of the stone at the north east corner of Maryland, tri-state commissioners appoint Lt-Col James D Graham, of the US topographic engineers to confirm the work of Mason and Dixon. Maryland will gain two acres. | Tri-State Mason Dixon Marker, McClellandville, DE |
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