User:Closeapple/Illinois'

On the standard usage for the possessive of "Illinois" being "Illinois'" ending with an apostrophe, not an "s":

Undecided

Wikipedia's Wikipedia:Manual of Style#Possessives is contradictory, saying "Illinois's legislature" but then saying "For a singular noun ending in one s, there are two widely accepted forms". Also notes that there is still much debate about this.
Wikipedia's Apostrophe#Nouns ending with silent "s", "x", or "z" notes: The same principles and residual uncertainties apply with "naturalised" English words, like Illinois and Arkansas. — also has links to some sort-of-related discussions

AP Stylebook specifically says "Illinois'"^[1]
Chicago Manual of Style allows bare apostrophes for words ending in silent sibilants^[1]

UIS Writing Style Guide at the University of Illinois at Springfield: "Our preference for forming the possessive of proper nouns ending in "s" is to add only an apostrophe (Texas' flag, UIS' soccer team)."
Illinois Identity Standards Writing Style Guide at the University of Illinois at Urbana-Champaign: The older, 2010 version of the guide said: "Use an apostrophe followed by an s when indicating the possessive for names, even when the person’s name ends in s. Example: The Stevens’s dog, Illinois's football team." However, by the March 2015 version the guide changed: "The word "Illinois" is a singular proper name ending in an s. As such, only an apostrophe at the end is needed to indicate possession. Example: Illlinois' athletic teams."

Illinois Department of Veterans' Affairs - Honoring Illinois' Fallen
A History of the Illinois Judicial Systems: "Illinois entered the 1970s with a new judicial system, one that accommodated its citizens better than the judicial systems of Illinois' past."
Legislature: Laws of the State of Illinois - Ninety Third General Assembly - 2003 - Public Act 93-001 thru Public Act 93-663 — lists every Act passed by the state legislature in 2003 — "Illinois's" appears only twice, on pages 2746 and 2751, in the phrase "the fire department of the University of Illinois's Champaign-Urbana campus"; but "Illinois'" appears at least 12 times independently, plus 60+ times in the phrase "the Fund for Illinois' Future" — I quit counting after page 4635 or so.
Search Illinois Goverment (official state site): Illinois's matches only 128 documents compared to 101111 containing "Illinois" in some form

U.S. Supreme Court — Jonathan Starbl, "Gimme an S", 10/9/2006, Legal Times, quoted in the Language Log: "Scalia repeatedly referred to the possessive of Illinois as Illinois' rather than Illinois's. He has also shown other inconsistencies, such as his repeated use of the word Congress', which is inexplicable in light of his acknowledgment of the word witness's in his Marsh concurrence and his use of the word Congress's in his 2004 majority opinion in Vieth v. Jubelirer."

Ask the English Teacher: The Possessive of "Illinois" — Canadian explanation that the Globe and Mail style guide uses "'s" for French possessives

^ ^a ^b Freeman, Jan (2007-03-04). "Possessed by punctuation". The Word. Boston, Massachusetts: Globe Newspaper Company. Retrieved 2019-06-05. Illinois' and Congress', as AP would do it. [...] The Chicago Manual of Style says it's Kansas's and boss's, but when a final sibilant is silent, you can switch to apostrophe-only style: Camus' depression, Francois' flirtation, Arkansas' solons.