[quote author=Peter_MacDonald link=board=history;num=1064352830;start=0#14 Wider cloth was formed by joining two lengths to give a double width plaid. Thus, 60 inches is a little on the excessive side, 54-56 inches would have been more common.

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Peter is of course correct on the width issue.  Most modern bolts of fabric, however, come in a 60" width - except of course the REALLY good tartan!
I've seen some folks give a correct appearance to their plaids by taking the 60" wide material and running a false seam down the middle length-wise, by stitching a little "s" shaped fold in place the entire length.  This also reduces the width a tad, too....