I'm a little late to the party here. I recently discovered that someone in my extended family traced back our ancestry back to a John Donnelly from Maghera, Donegal, Ireland. He was born in 1834 and arrived in New York City in 1850. He married Catherine Langan (from Ballymore Ireland). He died in 1870. I'm not sure how accurate any of this information is, so take it with a grain of salt