The first question that a frightened world asked about Three Mile Island on 28 March 1979 was how long the place could be expected to stay on the map. As fear subsided enough to suggest that it might be there for a long time, the question shifted to the more curious, "How did the place get its unusual name?" That question is not simply answered; six years of curiosity and research have yielded more conjectures than proofs.
It is known that on 4 December 1749 Thomas Cookson, surveyor who in 1751-1752 laid out and purchased the town site for Carlisle, asked Thomas Penn for permission to buy the future Three Mile Island. When he died in 1753 Cookson had not completed his acquisition, but the land appeared in his estate records merely as an unpurchased, unnamed "island in the Susquehanna."
Cookson left two daughters, Hannah and Margaret, and a widow, Mary Thompson Cookson, sister of Brigadier General William Thompson of Middleton Township, Cumberland County. Mary soon re-married, this time to a surveyor colleague of Cookson, George Stevenson, said by 1770 to be one of the wealthiest men in Carlisle. In the course of acquiring four of the five iron furnaces west of the Susquehanna River, including those at Pine Grove and at Mount Holly Springs, Stevenson had learned something about real estate. When his stepdaughter Margaret died and his sister Hannah married Joseph Galloway, Stevenson resisted an attempt by the latter to force a legal division of the Cookson lands. However, Galloway prevailed. In 1766 Galloway visited the 334-acre island and reported it to be wooded, uncultivated and without a name.
So it remained until July 1770 when it surfaced as "Smith's Island" on the survey for an adjacent island. It lay about three miles south of Middletown, so named because it was halfway between the two important inland towns, Lancaster and Carlisle. In May 1772 the Pittsburgh Indian trader Daniel Elliott relieved Joseph Galloway of the ownership of the lower two-thirds of the island and vested the place with his name for a period exceeding the seventy-two years that it remained in his family. During that time the Pennsylvania Canal was constructed on the east shore of the Susquehanna River, adjacent to the island, but map-makers continued to use the Elliott name. These cartographers could logically have substituted the name "Three Mile" in recognition of the fact that untypically on that stretch of the artificial waterway there were no locks for a distance of three miles.
A succession of subsequent owners--Musser, Nissley, Greenawalt, Shireman-- left their names with the place. Perhaps in desperation, maybe only in a state of confusion because of the proliferation of owners' names, the publishers of the 1875 Atlas of Dauphin County termed it "Conewago Island." Four years later, when the wealthy James Duffy family of Marietta bought it, they gave it their name. James Duffy, Jr., built a substantial "tobacco station" on the island. However, the investment disappeared in the March 1904 ice jam and flood.
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