The Underground Railroad is believed, by some, to have used quilts to pass on directions using quilts "airing out" on porches or of windows. Though this is considered a myth, the stories give life to the traditional patterns used. To learn more about it here are some sites I've found.
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Historic and Antique Quilt info...
Patches from the Past -Scraps of Textile, Needlework & Quilt History
Quilt 1812: War & Piecing -from Barbara Brackman, Remember the 200th Anniversary of the War of 1812 through patchwork quilts. Check here for a period Technique or Style of the Month on the first of the month through 2012.