Living in the South?

I just found out that we live east of the Mason-Dixon Line (the line that traditionally divides the Northern states from the Southern states, or so I'd thought).  I didn't know that was possible, but here we are:

Apparently the Mason-Dixon Line was originally surveyed in the 1760s to settle a land dispute between Maryland and Pennsylvania (but including a survey of Delaware as well).  Only later was it used in reference to slavery boundaries.  But it doesn't actually divide the "free" states from the "slave" states, as Delaware (as well as Maryland and others) remained a "slave" state through the Civil War, despite not seceding from the Union.

So I'm confused.  Does this mean that we live East of "The South"?