In Texas, it's fairly common to hear "Ma'am" and "Sir," to address people you don't know well--particularly from people doing business or in the service industry.
One of our neighbors will frequently greet us with "Ma'am" or "Sir," as we pass his home, and I expect my nieces and nephews to respond with "Yes, Ma'am" whenever I give them instruction.
One odd cultural behavior I have noticed in Texas is how women are addressed in the workplace. It seems common for people to refer to female co-workers as "Miss Jennifer" or "Ms. Susan" while the male co-workers, even those in authority, are frequently referred to solely by their first names, "Bob," "Joe," etc. I always found it strange to hear, "Yes, sir, Bob. Right away," instead of "Yes, Mr. So-and-so."
But I suppose that many places in Texas are far more laid back, despite still clinging to some of the Southern traditions.