I first saw this border on a red, gray, and black wool quilt from the early 20th century. I think it's quite possible that that early quilt was made by someone who planned a three-strip border and then didn't realize until too late that the corners were going to be a bit awkward. But there was something about them that was appealing, and I knew one day I might want to make a quilt using something similar.
This top was pieced about 2 years ago and has been waiting for a border. It isn't as bold as on the antique quilt, but I think I'll like it. I really am going to try to get this layered and quilted soon. (The backing is ready. I just don't have a comfortable place to pin baste it.)