This faint and slightly difficult to read (as always, click on the image to enlarge, although this one will still be faint and slightly difficult to read) image is of the 1920 census. The Mulcahy family is living at 85 Luqueer St., and they're the first family on the page. Michael Mulcahy, father, isn't listed - he died in 1917. The head of the household is Mary, his wife, and all of her children are listed: James A., Matthew V., Joseph E., Michael F., Mary V., John A., Gerard E., and Vincent A. You can remember that in the 1930 census, James, Mary, Gerard, and Vincent were all still living in one apartment at 85 Luqueer St., none of them married or with children, as far as we can tell, while Matthew was living in the next apartment with his wife and kids, and Joseph (Papa) was living at 648 83rd St., recently married to Nana. Between 1920 and 1930, we've lost track of Michael and John. A Margaret appears on the 1910 census (which I'll post soon), but as she'd be 30 by 1920, I assume she'd left and gotten married, and as I have no idea to whom - though someone else might - she's untraceable, for me. John and Michael I could try to find.
In 1920, only Gerard and Vincent - who were 11 and 12 - had been in school within the previous year. John, at 16, and Mary, at 18, the two next youngest, had not. Mary Ann Madigan Mulcahy, the mother, lists no employment, but all of her kids work, apparently in only 2 industries between them. James, Matthew, and Papa all have occupations of either "mail clerk" or "clerk" (Matthew) for a "Railway" or "R.R. Off." (again, Matthew's is the one listed in different format. Perhaps he worked for a different company, or in a different capacity, or...?) Michael and John list their industry as "tool office" - John's occupation is "clerk," but I can't read the first part of the description, and I'm not sure what Michael's says: "[something]-maker."
Clearly, speculation and guesswork increases as you go back in time.