Harrison, after leaving his post but while still in the country, wrote his roughly ten-page letter to Bolivar, which is reproduced in full in both the Hall and Burr biographies. It left the former struck by Harrison's "deeply imbued principles of liberty". Burr describes the letter as "replete with wisdom, goodness, and patriotism…and the purest of principles".[79][80]

Private citizen
Harrison returned to the United States and his North Bend farm, living in relative privacy after nearly four decades of government service. He had accumulated no substantial wealth during his lifetime, and he lived on his savings, a small pension, and the income produced by his farm. Burr references M. Chavalier, who encountered Harrison in Cincinnati at this time, and described Harrison as "poor, with a numerous family, abandoned by the Federal government, yet vigorous with independent thinking".[81]
In May of 1817, Harrison served as one of the founding vestry members of the Episcopal congregation, Christ Church in downtown Cincinnati (now Christ Church Cathedral).[82] Harrison went on to serve as a vestry member through 1819, and then again in 1824.