No, not Scottish. Could be residual preferences from the 18th c. when woolens from Wales, Scotland, and England were dominant in North Am. markets. Even by the Civil War, plaids still common for enslaved clothing. No evidence that specific plantations lay claim to proprietary designs.

Thanks, that makes sense, although AFAIK the woollens exported from Scotland to the slavery economies were mostly plain osnaburghs (cheap, rough but tough), but my (very limited) knowledge is mostly post-1776.