My husband and I are in agreement that children should not call adults by their first names. It's always Mr./Mrs./Miss LastName. Now, if the adult says otherwise, then they may use Mr./Mrs./Miss FirstName. But they may never call an adult strictly FirstName. We see it as a respect thing.

It's not as common now, and much less formal, but it's still in use where prompted by parents. The children on my street address me and the other adult women neighbors this way, whether single, married, mothers, or childless.

Is this a Southernism for both whites and blacks or is it primarily African-American? Is it more common with females than with males?

I ask only because I grew up in the South for most of my life but my parents were not from there. My sister had some African-American friends growing up who called my mother "Miss Cindy" (I believe they were from Tennessee but it has been like fifteen years or more and I've lost contact with them) and I have an African-American friend who comes from a different state entirely who referred to a friend of her mother as "Miss Sophie." I never called the parents of any friends by that, it was always either Mr./Mrs. and the last name or first names.

No, it wasn't just among African-Americans. Everyone I knew did this.

Going back to the Faulkner story, I just realized that the protagonist, Miss Emily, is not married. So, that sort of cancels out that as an example (I had forgotten that in my previous answer).

I ask only because I grew up in the South for most of my life but my parents were not from there. My sister had some African-American friends growing up who called my mother "Miss Cindy" (I believe they were from Tennessee but it has been like fifteen years or more and I've lost contact with them) and I have an African-American friend who comes from a different state entirely who referred to a friend of her mother as "Miss Sophie." I never called the parents of any friends by that, it was always either Mr./Mrs. and the last name or first names.

Emmett, your theory sounds plausible. It may well be a carry-over from the 19th century South.

Although not necessarily the case for the novel, house slaves were often multi-generational care givers. Continuing to use the "Miss X" formula required no change upon marriage. It also simultaneously displayed respect and endearment.

BTW, I found this quote of the actress who played Scarlett's black Mammy:

Playing the Mammy of Miss Leigh was just about the biggest thrill I've ever had.

Hattie McDaniel

Even long after slavery ended, she was still showing respect to the 'Gone With the Wind' lead actress.

Emmett

Several decades ago, I think businesswomen would be normally addressed as "Miss Smith," "Miss Jones," etc. rather than worry about whether or not they were married and were a "Mrs."

Singer Tiny Tim used this form when addressing or speaking of women, as a form of respect (the woman he married was always "Miz Vicki", usually written "Miss Vicki" by newspaper people unfamiliar with the practice). He adopted this Southern form of address even though he was originally from New York city; apparently his own hometown didn't provide him with a title to use that was sufficiently courtly to suit his tastes.

One of my professors in college did the same thing. He also addressed male students as "Brother" plus the first name (I was "Brother Ron" whenever he mentioned me).