McKean, an Irish immigrant, writes his uncle hoping that Philadelphia remains free of the Yellow Fever:

            “Dear Uncle,

                … am under many obligations to you for your information respecting the state of that unfortunate country & the old neighbours – Also for you’re your well wishes for our prosperity in Business – Since we have begun we have done more than we could expect & our business increases every day. Our stock was but small when put together, but I am proud to say that both our credits was good. It was with great reluctance that I entered into business after my Father & Uncles repeated wishes not to do so, but I hope they will no longer view it in the same light … they were unacquainted with my situation & did not know the encouragement we had received. We had a few days ago received 2 boxes of linen from James Hamilton to sell for him. We have sold 1/3 of them … you will be so kind as let us know what quantity of old Flax seed remains on hands in Belfast… We are in hopes the Y.[ellow] fever will not return this season owing to the uncommon mildness of the weather and being so far advanced without the least talk of it. Our Quarantine Law is in full force and no vessel from the West Indies will be admitted to pass without riding her limited time. The most learned Doctors disagree with respect to its Origin, some say it is imported, while others say it originated here, but the former receives most credit … the Board of Health takes every precaution to hinder its return …”

            The death of 5,000 people from Yellow Fever in Philadelphia in 1793 was the worst epidemic in early American history. The theory of Dr. Benjamin Rush, a Signer of the Declaration of Independence, that the fever arose from the city’s urban filth and was not imported from the West Indies, was particularly disturbing to merchants like Irish immigrant McKean who feared permanent damage to the reputation of the port. It is uncertain if the writer was any relation to another Signer of the Declaration, Thomas McKean, who was the Governor of Pennsylvania and son of immigrants from Ireland – that “unfortunate country”, still politically troubled four years after the abortive French invasion and rebellion.