Where is the South?

There was no blogging Friday due to my firm's summer associate outing, but while we rode the bus back to D.C. there were some interesting conversations. (First of all, I revealed that I was a libertarian, which produced much befuddlement and consternation among those who formerly had good opinions of me as a right-thinking and sane individual.) Perhaps more controversial was our discussion the nature and location of "The South." It began with the assertion that D.C. is a Southern city and rolled merrily along from there. Some relevant issues we highlighted in determining whether an area could be included in the South:

-The Mason-Dixon line
-History of secession
-Slave v. free states
-Self-identification by residents as Southern and chosen association with "Southern culture" (whatever this means) and historical narrative
-Percentage of immigrants from other regions and number of generations who have lived in the same place
-Whether entire states had a consistent identification as Southern or whether states could be Southern even if a significant portion of the population rejected Southernness (NoVa, possibly Atlanta)
-Conversely, can regions of non-Southern states be Southern (example given was Kentucky/Indiana border, AKA Kentuckiana)?
-Texas: is it the South?
-How long does one have to live in the South before becoming Southern and how does one become non-Southern after leaving the South?
-What is "The South" defined with respect to? The North? The Mid-Atlantic? The Midwest? The more subdivisions are permitted, the smaller "The South" becomes.

We had some strong sentiments expressed by people from the D.C. suburbs that D.C. is not Southern and neither is Maryland or Virginia (at least NoVa). I think a lot of this was people imposing their own reluctance to be identified as Southern on the discussion, but I am suspicious generally. My quick and dirty definition of the South:

Louisiana, Mississippi, Alabama, Georgia, Arkansas, North and South Carolina, Virginia, D.C., Kentucky, Tennessee, southern Missouri, eastern Texas, and northern Florida.

Thoughts?