I found this site with an updated list on Wal-MArts that DO NOT allow
camping.  I believe a majority of the Sams Clubs and Wal MArts do allow
it.  Not that I would feel very safe in a Wal-Mart parking lot.  They
have a very poor track record for parking lot safety.

http://www.freecampgrounds.com/walmart_nocamping.aspx

http://www.walmartmovie.com/crime.php

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'84 Westfalia, 1.9L
'73 FJ40, 2F