Taking a break and working on Mervin's. I'd never heard of it. It was a department store based in California. It went out of business in 2008.
In 1978, it was in three states---California and Nevada for certain. The third state at this time is unclear but likely Texas. There was a big expansion starting in 1986--Georgia and Florida were mentioned in this expansion. Georgia and Florida were opened in 1986 and closed in 1997. All other states were opened and closed between 1986 and 2008.
At its peak, it had stores in 10 states. Since there were 16 states mentioned overall, it's difficult to pinpoint which states had stores in the late 80s and early 90s.
But it's clear that the majority of the stores were located in California and Nevada. Next runner up was Texas. Since it was most prevalent in California and Nevada, it seems likely to me that John Doe is from Nevada or California.
I'm listing open and closed dates I've identified for each state I've found mentioned anywhere. This will at least tell us with certainty which 50 states did NOT have Marvin stores.
Arizona (closed 2008)
California (established 1948, expanded 1962-1975, closed 2008)
Colorado (closed all stores 2007)
Florida (opened 1986 - closed 1998)
Georgia (closed 1986 - closed 1998)
Idaho (closed 2008)
Louisiana (closed 2006)
Nevada (closed 2008)
New Mexico (closed 2008)
Michigan (closed 2006)
Minnesota (closed 2005)
Oklahoma (closed 2006)
Oregon (closed 2007)
Texas (closed in 2006 and 2008)
Washington (closed 2007)
Utah (closed 2008)
http://en.wikipedia.org/wiki/Mervyns
http://www.fundinguniverse.com/company-histories/mervyn-s-california-history/