I gather a lot of people ship their quilts all over the country, either to quilters or the recipient. Here in Canada postage is brutal. So the smaller the package the better.
My sister took 3 full sized quilts back to BC in a regular suit case along with all her original stuff. We packed them into a vacuum bag we bought at the dollar store. They compressed down to less than two inches. We had to open it once though, to check they were alright. The trick was to fold them down to the correct dimensions. I have been taught to fold and store my quilts folded on the diagonal so there are no fold lines set into them.