The 1910 and 1920 censuses show him as born in Ireland. However the 1930 census shows he was born in Scotland. All show he immigrated around 1906.
On board the S.S. Furnessia when it landed in NY on Sept 25, 1907 was a George Sleigh 29 who was born in Edinburgh, Scotland, but was Irish. He was headed to Pittsburgh, PA. His father's name is hard to make out. It looks like it would be Dan.
A WWII draft registration card for George Sleigh lists him as living at 711 Kelley St, Pittsburgh and that he was born July 12, 1878 in Edinburgh, Scotland.