The timing on this question is extremely important. Until the later part of the 19th century, the middle class in America was a small percentage of the population. They almost always had domestic help.
After the Civil War, the north began to industrialize heavily. Jobs increasingly became open to women. Mill towns in Massachusetts, e.g., built dormitories expressly for women workers. These jobs paid much better than being a domestic and started pulling women out of the home.
By the 1890s, you start reading about the “servant problem” everywhere. Houses couldn’t compete on salary with jobs outside the house. The more Americanized the women, the more likely she was to take advantage of the opportunities. Households tried to attract workers from the exploding immigrant population, but they were largely unsatisfactory because of language barriers, class barriers, and lack of familiarity with the changing and modernizing American kitchens.
The percentage of middle class homes with help declined steadily until WWI and then fell precipitously. The war gave even more opportunities to lower class women at higher salaries. And by then a burgeoning number of gas and electric appliances made it more feasible for a women to run a household on her own. Ironically, standards also rose during this time. If every house had a vacuum cleaner then it was expected to be a cleaner house.
The south was a different universe, since it had the same pool of cheap black labor throughout. There was little industry to attract women and only a tiny percentage of immigrants settled there.
The notion that a woman can and should run a household by herself was almost completely established by the 1920s and came after a full generation that trended that way because of economic reasons, technological innovation, and a new sense of women’s capabilities. It’s not in the least modern, if by modern you mean today.
I’m pulling this summary from a lot of reading about food in that period, but I can give some cites that should be useful.
Arlene Voski Avakian & Barbara Haber, eds., From Betty Crocker to Feminist Food Studies: Critical Perspectives on Women and Food (Amherst, MA: University of Massachusetts Press, 2005) Esp. Leslie Land, Counterintuitive: How the Marketing of Modernism Hijacked the Kitchen Stove.
Tim Cresswell, On the Move: Mobility in the Modern Western World (NY: Routledge, 2006)
Dave Walter, ed, Today Then: America’s Best Minds Look 100 Years into the Future on the Occasion of the 1893 World’s Columbian Exposition (Helena, MT: American and World Geographic Publishing, 1992)
Christine Frederick, The New Housekeeping (New York: Doubleday, 1926). (See a pertinent excerpt at: http://historymatters.gmu.edu/d/5301/)
Jane Lancaster, Making Time: Lillian Moller Gilbreth – A Life Beyond “Cheaper Than the Dozen” (Boston: Northeastern University Press, 2004)