All McGirts LOOK at Berkeley Co. SC Web-site
My Grandmother was a MCGUIRT, I traced my 7th Great-Grandfather, back to Craven Co. SC., Craven Co. went from Charles-Town, to NC, at Cape Fear. Later Craven Co. became Berkeley Co.SC. There are a BOAT-LOAD of McGirt's in Barkeley Co. SC. I believe that this might be where the McGirt's started.
Also, - my 3rd Great-grandfather's mother was a McGuirt, his father was an Native American. His mother had 5 children, by 5 different men. she had a daughter that was a mulotto, her name was Lynda, Lynda had 3 children, out of weblock, they were molottos also; their names were Martha, b. 1842, James F., b. 1847, and Mary b. 1848.