… When this happens:
1. Pour the cup of fresh coffee, shake the cobwebs out, start searching the 1915 New York Census for 142 West 126th St., Manhattan.
2. Use Stephen Morse’s invaluable One-Step Tool for finding New York Assembly Districts/Election Districts for 1890-1925.
3. Locate the relevant set of images at Ancestry.com. Excellent.
6. Page through the image set carefully, page by page, beginning to end, checking which image numbers correspond to which actual census sheet numbers (penned).
7. Realize that Image No. 3 contains Sheets 4 and 5, and Image No. 4 contains Sheets 8 and 9.
GUESS WHAT IS ON SHEETS 6 AND 7?
No, really, guess.
Now, the New York State Library in Albany says it has original manuscripts of the 1915 and 1925 censuses, so the missing pages would appear to exist in some form somewhere, which is something. And missing census pages do happen in microfilm sets. See this amusing post from Ancestry Insider about missing federal census pages. Well, at least I hope you find it amusing. I personally plan to amuse myself by banging my head into the nearest wall.