Forename name Mary Ellen is from US social security record; maiden surname Boggs and "from Derry" is from my son's mother-in-law; 1930 census lists her as married to John Snellinger and using the name "Minnie" and that census notes her as age 35 (i.e., born about 1894-1895) in "north ireland" and immigrated to US in 1913.
Ellis Island shows one Minnie arriving in 1913, on the Cameronia, last residing in Carndonagh, Ireland, so it would appear that she should be in the 1911 census, but, Carndonagh is way up by Malin head, yes? So, not knowing my Irish geography all that well, which of the 1911 entries for Minnie Boggs is most likely the right one?
To compound that, the Ellis Island site also shows another Minnie of about the same age arriving a year earlier, also from n. ireland. So.....which is the right minnie.