Originally Posted by bluebird
If you cut your border pieces on the length of the fabric (along selvage side) it doesn't stretch.
This is what I do. I cut all my borders on the straight-of-grain (along the salvage), sew the borders together, sew them to the quilt, miter the corners.
There are times when I middle border was pieced, I still followed the above for the inner border(s), then followed with the outer border(s).
But I love long straight borders and mitered corners. That's just me.