Being the curious creature that I am, I contacted Mary V. Thompson, Research Historian at Mt. Vernon Estate & Gardens, and author of the book, "In the Hands of Good Providence" - Religion in the Life of George Washington, to find out more about how Washington maneuvered around the Pennsylvania emancipation laws. The ever responsive Mary Thompson replied by pointing me to her article, Different People, Different Stories: The Life Stories of Individual Slaves from Mount Vernon and Their Relationships with George and Martha Washington, which informs the reader:
In November , when the presidential household moved in, there were up to thirty people living on the premises: Washington, his wife, Martha, and her grandchildren, Nelly and G. W. Parke Custis; Chief Secretary Tobias Lear, his wife, and the three male secretaries; eight enslaved Africans from Mount Vernon; and about fifteen white servants.
Pennsylvania's government was the first in the Western Hemisphere to take steps to abolish slavery. In 1780, it enacted the Gradual Abolition Law — prohibiting further importation of slaves into the state. But the law also respected the property rights of Pennsylvania slaveholders by freeing only the future children of enslaved mothers. Children born or living in the state before March 1, 1780, remained enslaved for life (or until 1847, when legal slavery finally ended in Pennsylvania). The 1780 law was lax regarding non-resident slave-holders living in Pennsylvania on a temporary basis. It provided a mechanism for these enslaved to legally obtain their freedom, provided they established a 6-month residency in Pennsylvania. To prevent this, non-resident slaveholders simply interrupted the residency by taking their slaves out of the state before the 6-month deadline. A 1788 amendment prohibited this rotation of slaves in and out of Pennsylvania. But Washington knowingly violated this amendment to the Gradual Abolition Law. He [privately] maintained that his presence in Philadelphia was a consequence of its being the national capital, that he remained a citizen of Virginia, and he was careful that neither he nor his slaves spent the six continuous months in Pennsylvania necessary to establish legal residency. Nine enslaved Africans worked in the President's House: Oney Judge, Austin, Moll, Giles, Paris, Christopher Sheels, Hercules, Richmond, and Joe (Richardson). Click here to read biographical sketches. Gradually, the enslaved Africans in the presidential household were replaced by white German indentured servants.
As a result, Washington devised a solution to his dilemma, which involved the planned distribution of a timely set of slave perks. The Mary Thompson's article goes on and describes the scheme:
It was during their years in Philadelphia that the Washingtons realized that there might be a problem with the status of their slaves who were in the city. On April 5th of 1791, Attorney General Edmund Randolph called on Martha Washington in the Philadelphia executive mansion, to let her know that three of his slaves had just told him they were going to take advantage of a Pennsylvania law, which allowed them to claim their freedom after six months residence in that state. (54 - Tobias Lear to George Washington, 4/5/1791, The Papers of George Washington, Presidential Series, Volume 8). When informed about this development, George Washington suggested, as a precaution against his and Mrs. Washington's slaves attempting a similar exodus, that they be sent back to Mount Vernon.
Edward Lawler also wrote a companion article, Washington, the Enslaved, and the 1780 Law. Here, Lawler counted up the out of state excursions for the President and his wife, Martha. According to Lawler, "The Washingtons made 14 trips from Philadelphia to Mount Vernon between March 1791 and October 1796, and used the trips to rotate their slaves out of Pennsylvania." The longest of which was Washington's tour of 1887 miles through the southern states (April 7 to June 12, 1791). Now, all together, that's a bundle of frequent travel miles, and that's not even counting the likely thousand trips back and forth from the slave quarters to the executive mansion via their underground slave tunnel. The usual way in which plantation slaves redeemed their accumulated perks was by enjoying a plantation owner sponsored dance, whiskey, and a big meal feast. You gotta figure that during the slave respites' in Mount Vernon the place had a lot of parties, 'cause in Washington's mind a perk, such as inscribed on the Liberty Bell, was out of the question - I do not think they [the slaves] would be benefitted by the change [to a free status], yet the idea of freedom might be too great a temptation for them to resist. At any rate it might, if they conceived they had a right to it, make them insolent in a State of Slavery. Washington to Tobias Lear, 4/12/1791
The strategy he hit upon, which he said he wanted done "under pretext that they may deceive both them and the Public," was to send them home to Mount Vernon with the story that they were either accompanying Mrs. Washington, were needed to cook for her at home, or to give them the opportunity to visit their own families and friends. This would effectively prevent any of those who were old enough to claim their freedom, from meeting the residency requirement after their first six months in the state.(55 George Washington to Tobias Lear, 4/12/1791, The Papers of George Washington, Presidential Series, 8:85-86).
Two weeks after Randolph's initial conversation with Martha Washington, Austin was sent home, as Washington explained to her niece, for the purpose of seeing his friends." Mrs. Washington showed that she, too, was capable of deception when it came to dealings with slaves, because she went on to say that "his stay will be short indeed[.] I could but illy spare him at this time but to fulfill my promise to his wife.(56)
Washington's secretary, Tobias Lear, later consulted with the Attorney General and fleshed out a more detailed plan to prevent any of the Mount Vernon slaves from being emancipated because of the Pennsylvania law in the future, but it differed little from the original strategy devised by the president and the first lady. Interestingly, Lear, who was a New Englander, was greatly troubled by both the plan and his part in it, and confided to Washington that "no consideration should induce me to take these steps to prolong slavery of a human being, had I not the fullest confidence that they will at some future period be liberated, and the strongest conviction that their situation with you is far preferable to what they would probably obtain in a future state. ... (57 Tobias Lear to George Washington, 4/24/1791, The Papers of George Washington, Presidential Series, 8:131-132).