So what are you seeking in this topic?
I'll be physically present in my state for more than 50% of the time and I would have resided between 3 and 3.5 months in my state by the time I submit my N400 application. (I write "between 3 and 3.5 months", because I don't know exactly what date count to establish one's residence).
This made me wonder where the USCIS draws the line. As you mentioned, the letter of law (8 CFR 316.5(b)(5)(i)) says one could establish residency and then be physically absent from the state / FO district the remainder of the time. Note that, from the best of my perhaps incorrect knowledge (and please correct me if I miss something), the same law doesn't specify how to establish residency: I couldn't find anything in CFR Title 8 on what's the criteria to establish residency.
The closest I could find so far is 26 CFR § 301.6362-6:
However, this is for Title 26 (Internal Revenue), not Title 8 - Aliens and Nationality, so I don't know if the USCIS follows the same definition. But I couldn't find anything in Title 8 yet. As a result, I wonder if the USCIS has clearly stated how they decide from which date the applicant has established residence in a US district/state for the 3-month requirement.
I just saw that some threads got merged. My clarity, there are 3 questions (which I'll post here since threads got merged😞
What criteria does the USCIS use to decide when the applicant has established residence in a US district/state for the 3-month requirement? E.g., the driver's license issuance date, the date when the lease/mortgage, the date when the Internet/electricity/gas/water start, etc.? for example, if the driver's license issuance date = April 1 and the lease/mortgage starts April 10, did the individual establish residence on April 1 or 10? In other words, can they submit the N400 application on July 1 or July 10?
How does one count the 3-month requirement to apply for naturalization in a US district/state? Both the USCIS policy manual and the CFR says one count the 3 months from when the applicant has established residence, including any absence from the US. But as was mentioned earlier, if someone established residence and leave the US for the remaining of the 3 months, it seems quite extreme. So where does the USCIS draw the line? At 50% time in the US state, except if some special circumstances (e.g., job requiring to travel all the time or micro-states)?
Must the USCIS abide by the Code of Federal Regulations (CFR), or is the CFR just a set of guidelines that aren't legally binding? This question is motivated by the fact that answers to questions 1 and 2 often refer to the CFR and/or the USCIS policy manual, and that the the USCIS policy manual is not legally binding. Because if the CFR is not legally binding, then perhaps we should also read the US code to try to answer the first two questions.