As long as I can remember I have seen Pipe bands & Kilts @ St. Patrick's Day parades. Having lived in Scotland and being the stupid git american tha asked, while visiting in Ireland, "Where can I find a kiltmaker ?" And to be immediately laughed at. "Silly Americans. Kilts are Scottish." was the reply by shopkeepers. I know kilts are Scottish, but at the time I thought they were Irish too. I've tried to find out what the connection is. When in Scotland we celebrated St. Andrew's Day by wearing our kilts.
St. Pat's Day in Ireland up until the late 1990's was a holy day. A day to go to Mass. Then the Irish figured out they could make some money from having Americans celebrate St. Pat's in Ireland. Then kiltmakers, located in Scotland, found a market for "Irish Kilts" and started producing tartans per county. I personally know a gentleman, from when I lived in Edinburgh, that grew up in Northern Ireland, that told me that he had worn a kilt as a boy. It wasn't like the Scottish kilt with a tartan. His was a specific tweed. Anyway back to my painstaking question. Why tartan kilts from Scottish clans on St. Patrick's Day.