Ma'am Update

Excerpted from Wikipedia:

Ma'am literally signifies "my lady."

Usage of "Ma'am" is common in the United States and in Western Canada. In the past the term was in theory to be used only for married women, but it has become common courtesy to use this term for all adult women, rather than to attempt to presume a marital status based on age or other appearances. The term formerly in common usage for unmarried women, "Miss," is now usually reserved only for children and young ladies of school age, for extremely formal usage in which the woman's marital status is known, or if the woman in question has made it known that that she prefers said term.