There's New England: (Maine, Vermont (which I'm counting even though it has no coast line), New Hampshire, Massachusetts, Rhode Island and Connecticut. Then there are the Middle Atlantic States: Delaware, Maryland, New Jersey, Pennsylvania, Washington D.C.,and New York. And the Southern Atlantic states: Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, and West Virginia. (Although some put Virginia and West Virginia in the Mid-Atlantic--I could not find a consensus on this).
Each region has its own culture, shaped by the people who settled there, the terrain, history, economics, etc. We've even had a war over the differences between the states. So, yes, saying "ma'am" will get you kudos in some areas and dirty looks in others.
Don't worry - not even people who were born and raised in West Virginia (like myself) can find a consensus on that one! :-P I personally identify more with the southern states, although I'm from North Central WV. People from the northern panhandle though may identify more with the north, the eastern panhandle tends to lean more toward DC's culture, and of course when you go more south, the more southern it gets.
When I worked in a call center up home, we took calls for a major telecommunications company and handled their southeast branch. I actually took calls from people in the same area in which I live now. We were told in training not to call them "ma'am" or "sir" because they may take it offensively, and I thought that was so odd - isn't the south where using those terms are most common? I didn't grow up saying ma'am/sir, but I really took to habit of it after moving to Alabama. Now I'm so afraid that when we move back, I might offend someone with it, since it's not nearly as common up home (at least in my region of the state).
There are some things you just have to “know” about places, even if they aren't so obvious on the surface. Trust the locals. If nobody swims in Piranha Pond, or drives down State Street after dark, or takes a shortcut through Old Man Crankypants’ pasture, there's probably a good reason.
I can't even stress how important this tip is! We have a river up home that is notorious for being quite treacherous in some places (whirlpools, eddies, riptoes, and one spot that is actually so deep they cannot measure it). So many out-of-towners, mainly college kids, would come in, hear the warnings but when they went to see the river, figure "it can't be that bad," as it really didn't look that bad on the surface. You truly had to be a local, or listen to a local, to know which spots were OK to swim in and which ones weren't. It looked like just another small West Virginia river running in a valley. As a result of that "Oh, it can't be that bad, the locals must be exaggerating" attitude, that river has had way more than it's fair share of drownings over the years.