Kilts are now often seen in the Borders but tartan trews, which are probably more historically accurate for southern Scotland, are still very popular.
At the Muster of the Clans in Selkirk last year, the Chiefs of Clans Scott and Borthwick both wore trews, as did the gentleman who is petitioning to be recognised as head of Clan Irving, but some Border clans, including Kerr and Nesbitt wore kilts.