Just a few more links from historians of Black History, the Underground Railroad and the 1990's-born myth of quilt signals:
http://en.wikipedia.org/wiki/Quilts_...round_Railroad
http://www.antiquequiltdating.com/Th...ng_Slaves.html
and
http://www.quilthistory.com/ugrrquilts.htm
All of the above links have extensive bibliographies.
As a historian myself, I think that the following quote from Quilt History says it best: "We have to conclude that there was no special role quilts played in the Underground Railroad. While no one can prove a negative, it seems unlikely that quilts were used as a directional code. Worse, this type of popular myth belies the hard work and dangers faced by the true heroes of the Underground Railroad.
When myths are not dispelled and the general public is allowed to believe anything, it hurts the truth of the culture and propagates false truths. History would be far better served if actual research was done on this topic so that we might honor the people who truly deserved it such as Harriet Tubman and Levi Coffin, rather than just endlessly repeating discredited myths and gossip. "