Hey! I can partly answer this one. But first, a few important points:

I would argue that the most important thing to recognize is that live-in servants were never all that common in the US, although they were more common in the urban northeast than elsewhere. In 1880 in the northern US (North of the Mason-Dixon, East of the Mississippi) there were 92 domestic servants per 1,000 families. By 1920 this sunk to 39 servants per 1,000 families. These numbers were lower elsewhere. So, while employing a servant was represented as a middle-class norm, it seems like fewer than 10 percent of families had them, at least by 1880. Servants were endlessly discussed in the popular media during the second half of the 19th century, but reading these accounts you might get an exaggerated idea of just how common they were.

Another important thing to note is that what we think of as a live-in servant (a uniformed maid with a room in the attic) is only one model of service. Another one would be the “hired girl,” a girl or young woman who may be from a similar social class as their host family, lived in close quarters with them, and who helped with agricultural or domestic tasks, often on a short-term or seasonal basis. This was especially common in rural areas and on farms. This kind of informality is the norm, rather than the exception, in the history of domestic service. Even today, babysitting, nannying, and housecleaning are all extremely informal industries.

Ok. But you asked about live-in and live-out service, particularly in wealthy households. I can’t answer this exactly, because you would need to be more precise about what we define as “wealthy” vs. “middle class,” and because I’m not sure the data is out there anyway. But if there was a watershed moment, I would put it in the early 20s. This was driven by a number of factors. One was advancing technology and electrification, which automated or eliminated some of the roles servants played (although some historians overstate this, I think). Another was the generally disruptive effect of World War One; following this point you see a much greater embrace of a simplified, “modern” home life. The third factor was the great migration of African Americans from the south to the north. During this period, African American women became increasingly overrepresented in domestic service. For white women, working as a servant was often seen as a temporary step before getting married, while black women were far more likely to work their entire lives, including after marriage. In a survey of servants from the early 1920s, 80% of white servant women said they preferred to live in, while only 36% of black servants said the same.

I’m sorry I couldn’t give you a precise answer to your question. If you do want to read more, I’ve included sources at the bottom of this post. I’ve been working from my own memory of these books, so its possible there may be more precise statistical information within them, if you look them up. I suspect that David Katzman’s book would be the most helpful.

Katzman, David M. Seven Days a Week: Women and Domestic Service in Industrializing America. New York: Oxford University Press, 1978.

Salmon, Lucy Maynard. Domestic Service. New York: The Macmillan Company, 1897.

Strasser, Susan. Never Done: A History of American Housework. New York: Pantheon Books, 1982.

Sutherland, Daniel. Americans and Their Servants: Domestic Service in the United States from 1800 to 1920. Baton Rouge: Louisiana State University Press, 1981.