Dear Deborah The spelling of my name as you see is Mckay ,although my aunts & uncles are spelt Mackay this came about when my grandfather was signing my fathers birth certificaate he accidently missed out the A henceforth our branch of the MACKAYclan became McKAY . So it is possible that immigrants from Scotland on landing in the new world with little if no writing capabilities gave their names to immigration officials who mispelt them .You also find thatsome Mckays pronouncing themselves mcKAY rather than mckiethis is usually due to phonetics I hope you are following this . Tracing Scottish clansurnames is a futile occupation as most clanswere situated in particular areas of Scotland ,and as they all had the same surname were often refered to by there first name or as(mac means the son of) were often called such things as jocks loon etc. Jock being the boys father get it. The Mackay clan as all clans originated in Ireland from the Celts.