Gaslight ER.
Mighty fine research.
It wasn’t until November 2008 that the fact of Chet Arthur’s father’s fatally (for Arthur’s claim to be an NBC) delayed citizenship oath became publicly known or even suspected.
William Arthur emigrated from Ireland to Canada, not the United States. William Arthur migrated to the Province of Lower Canada on date uncertain, circa 1819-1820. Lower Canada would now be in the Province of Quebec. Chester Arthur's mother Malvina met his father while William Arthur was living in Canada.
Chester Arthur was born in 1829. His father, William Arthur, was naturalized 31 August 1843.
Chester Arthur became Vice President and then President in 1881.
Of course, the naturalization was public record since 1843. William Arthur's ctizenship was published in Russia in 1881, in Novoe Vremya, and translated and published in the New York Herald, the largest circulation daily in the United States. The essence of it was published in the Brooklyn Daily Eagle in 1881. "Gen. Arthur is an unnaturalized foreigner," was published in the New York Times, Dec. 22, 1880. And, of course, Arthur's citizenship was the subject of a book published in 1884 while Arthur was still in office, "How a British Subject Became President of the United States," by A.P. Hinman. It was not that nobody knew. It was that nobody cared about your crackpot theory then any more than they do now.
It had to wait until the 21st century for the birthers to understand that William Arthur was a got-off-the-boat Irishman and preacher in a dozen churches.
Arthur P. Hinman was hired by the Democrat party to dig dirt on Arthur prior to his assuming office. Dig, dig, dig led to his book. As the book notes, "Entered according to Act of Congress in the year 1884, by A. P. Hinman, in the Office of the Librarian of Congress at Washington, D. C."
As the 1884 Hinman biography of William Arthur shows, William Arthur did not emigrate from Ireland to the United States, but to Canada, and it was in Canada where he met Chester Arthur's mother. They married in Canada. As Chester Arthur's mother was a United States citizen, any challenge to the citizenship of Chester Arthur had to rely on his father not being a United States citizen at the time of birth.
Amazingly, after your thorough research and due diligence, you concluded, "It wasn’t until November 2008 that the fact of Chet Arthur’s father’s fatally (for Arthur’s claim to be an NBC) delayed citizenship oath became publicly known or even suspected."