Saturday April 6 is National Tartan Day in the United States. Clothing featuring tartan plaid is often worn by Scottish Americans taking part in National Tartan Day.
While I don't consider myself Scottish American, but am of Scottish extraction on my mother's side of the family.
Locally there is a big annual celebrtation called Tartan Day South. The have events which run the full gamut of traditional highland games of strength, bag pipes, celtic festival activities, food, and fun.