Abolitionist, Welsh republican radical, publisher, Baptist minister, pioneer and adventurer Morgan J. Rhees fled to the United States in 1794 faced with arrest for his political work in Wales. Between 1793 and 1794 Rhees published Cylchgrawn Cynmraeg, the first political magazine in the Welsh language. Rhees traveled throughout the United States and its western territories on horseback 1794-1795, preaching emancipation and republican ideals while searching for a suitable settlement for Welsh immigrants. In 1797 he and his wife Ann Loxley Rhees founded the town of Beula in western Pennsylvania with land purchased from Benjamin Rush. The settlement was a failure; the land was ceded back to Rush in 1802. Rhees remained active in republican politics and encouraged Welsh emigration. Rhees was the great grandfather of Nicholas Murray Butler, President of Columbia University.

The collection includes two diaries of his American tour (one is made up of his rough travel notes, the other is in edited form for circulation), a memorial volume of manuscripts about his wife (Ann Loxley Rhees) prepared by his daughter Eliza (Mrs. Nicholas Murray), and 1851 passport of Nicholas Murray, a letter of Thomas Chalmers Murray to his sister Mary Jones Murray Butler (the mother of Nicholas Murray Butler, President of Columbia University), correspondence between Welsh historian Gwyn A. Williams and collection donor Mary Butler Brown, an essay entitled "Morgan John Rhees and Beula" by Gwyn A. Williams, Ann Loxley Rhees's valedictory oration on graduation from Philadelphia's Ladies Academy, an address on female education ca. 1789, family obituary clippings, poems, misc. items, and a photograph of Ann Loxley Rhees. An edited version of substantial sections of the diaries of M.J. Rhees was published in John Thomas Griffith's 1910 biography and miscellany of Rhees and his family, a copy of which is included in this collection. An edited version of a previously unpublished section of the diary, from May 2nd to July 9th 1795, was published in Northwest Ohio History (vol. 80, no. 2), but it is an unreliable transcription containing many inaccuracies, according to Dr E. Wyn James of Cardiff University, who is working on a new edition of the M.J. Rhees diaries.