See below for some helpful tips related to citation formatting, both in general and specifically to this article. While not required for promotion, I'm a firm believer that a Good Article should still be a good article.
Some photos would be nice. Strictly speaking, the only illustrations in the article are the highway marker graphics and the interactive map. They are correctly tagged and captioned, so this is a technical pass on this criterion.
Overall:
Pass/Fail:
Holding for improvements. I'm feeling generous on the prose since I've basically rewritten all of the issues for you in my comments.
Lead
"The southern terminus is at U.S. Route 166 (US-166) south of Edna and the northern terminus is at US-160 west of Altamont."
This is a compound sentence, because if you split it in half at the conjunction ("and"), each half forms a complete sentence. As such, it requires a comma in front of the conjunction.
"K-101 passes through mostly farmland except the section within Edna."
The word "mostly" is an adverb, and adverbs modify verbs, adjectives and other adverbs. This sentence reads poorly because it's positioned to modify a noun by trailing the preposition "through". You should shift it next to the verb "passes".
"K-101 proceeds north through farmland to a crossing over Hackberry Creek."
This is another place to trim excess words. You can assume that a road crosses over a creek. If it didn't, it would be worth mentioning the tunnel they used to cross under the water body.
Try "K-101 proceeds northward through farmland and crosses Hackberry Creek."
"The highway passes by a former airport just after an intersection with 9000 Road."
Roadways are linear features, and it helps to keep the geographic progression intact without jumping backwards. It's a minor point, but it is a little mentally jarring, especially on such a short road/short description.
Try "The highway intersects 9000 Road before passing a former airport."
"The roadway crosses over Richland Creek before reaching its northern terminus at US-160 west of Altamont."
So the suggested copyedit of that last sentence will mean a tweak here for some variety.
Try "K-101 crosses Richland Creek south of the intersection with US-160 west of Altamont; this intersection marks the northern terminus of [K-101/the state highway]."
So the second paragraph is functional, but it's a bit boring. For a highway this short, it might not be a good idea to essentially reverse course and redescribe parts of the highway now in terms of traffic levels.
After the first sentence of the first paragraph, you could insert one that says this is the location KDOT determined had the highest traffic count on average.
Then do something similar with a sentence about the lowest traffic count at the northern terminus. Now you've fleshed out the description of the route, and added a little variety to what is otherwise a fairly mechanical description.
Of course, these suggestions just gutted your second paragraph and bulked up the first a bit. So I would divide the first paragraph in two, say right after the mention of the Edna Cemetery. (This then plays into the history section a bit.) If done, just tweak word order and usage a little so that every paragraph doesn't start with "K-101...".
That then leaves the NHS discussion. This should be fleshed out just a bit more. Try something like "No section of K-101 is listed on the National Highway System,[7] a network of roads important to the nation’s economy, defense, and mobility,[new cite] but it connects to the system at each terminus.[7] (There is {{FHWA NHS}} to supply a citation to that webpage, by the way.) This could be tagged onto the end of the second paragraph, or run solo as a third paragraph. (Normally single-sentence paragraphs are bad, but since this is slightly different topic than the rest of the RD content, it makes a bit of sense to run it separately. You could divide my suggested sentence in two at the FHWA cite just to make it a two-sentence paragraph.)
In the lead, you've rounded off the length of the highway, which is a good thing for readability. Here, you've used more precise lengths. There's a time and a place for that level of precision, and this isn't it, I don't think.
Various sentences would read better if they were in the active voice, i.e., "who did what" instead of "what was done by whom".
"The State Highway Commission of Kansas (SHC) first designated K-101 on a half mile (0.8 km) of roadway between US-166 and Edna on May 26, 1937." (I don't think you need to explain the relationship between the SHC and KDOT, but if you do, that's a good time to use an explanatory footnote so that it doesn't interrupt the flow. Otherwise, it's also a good time to let wikilinks do the explaining for you, but sadly, the KDOT article doesn't explain the SHC was renamed, or even if the SHC still exists as a part of the modern department.)
"They extended the state highway another half mile (0.8 km) to the Edna Cemetery [in a resolution approved on May 10, 1950/on May 10, 1950]." (Mentioning the resolution may be superfluous as the key point here is the date not the mechanics of approving said extension.)
The whole 1954 stuff should be a separate paragraph. It's a topic unto itself and separate from the first few details. Then that content needs a copy edit so that it flows together better and so that it has just generally better wording. The phrase "proposed to extend K-101" just grates in my ears for some reason. Maybe "proposed an extension of K-101"?
The current second paragraph is a good example of content on a single topic put together. It would be nice if you could find out when the tracks were removed, but absent a source for that, the current wording works. I would do a little digging to make sure that the removal didn't happen earlier just because you have a 21-year jump in time. If you found out when they were removed, you might also find out a reason for the removal, say that the line went out of service because X reason.
The last paragraph here has a bit of unneeded detail, and frankly, I get suspicious whenever I see seven consecutive footnotes.
The first sentence is good.
"The segment of K-96 that made up the northern terminus of K-101 became a newly rerouted US-160." How about "KDOT rerouted US-160 to replace K-96."
"Prior to this US-160 turned north onto US-75 east of Independence. It continued north to US-400, which it followed east to its current alignment." I'm not sure that you need this, or that you need quite this level of detail.
Check WP:USRD/AASHTO, and I'll bet you'll find an approval for the reroute to simplify some of the citations. I think if you check there, you may find that the change was the reverse of the implied order of events you wrote, especially if dig into the AASHTO archive and pull KDOT's application. It may not be so much that K-96 was truncated as KDOT wanted US-160 moved and K-96 was truncated as a result. In any case, I'd be careful to keep whatever revision concise and focused on how it impacted K-101. "In 1998, KDOT wanted to move US-160 because A and asked AASHTO for approval. Once approved, the department rerouted US-160 and truncated K-96. Since then, the intersecting highway at K-101's northern terminus has been US-160."
Major intersections
This is perfectly functional and doesn't need modification.
Referencing this table and referring back to the RD, perhaps the township names should also be mentioned in the prose. "just south of Edna in Elm Grove Township" and "west of Altamont in Mount Pleasant Township"
References
Footnote 2 uses "Staff" as the author, but other KDOT citations list the department name, which is the better practice. You should switch this for consistency.
Footnote 3 is missing a title and throwing an error message.
USGS publishes out of Reston, Virginia, so you should add the location. Unless a map has a variable scale, like Google Maps, the scale should be listed or "Scale not given" should be indicated. If the scale is determined from a library listing, and not from the source itself, use brackets. Also, it's a good practice to convert map scales from "1 inch = 10 miles" notation to a ratio like "1:633,600". (To convert, multiply the larger unit by the appropriate conversion factors to express it term of the smaller unit. 10 mi × 5280 ft/mi × 12 in/ft = 633,600 → 1:633,600 .)
You can use |type=Topographic map or similar to specify the type of map instead of defaulting to the generic "(Map)." in the output of the citation.
Footnote 7 doesn't need FHWA linked twice.
Footnote 10, et al., does not need the newspaper's location listed. Locations are listed for newspapers when they are not already included in the name of the paper. This has served as a form of disambiguation when trying to distinguish between multiple papers with the same name. "Which The Times? Oh, the one in London, not the one in Johannesburg or Chicago." Also, locations were traditionally listed in citations for books and such, but it was considered redundant to repeat them when already contained in another part of the citation.
Poking in because I know I use PressPass, and it does this automatically when generating the citation. If 420Traveler uses this tool (and I tend to recommend it to people that have Newspapers.com access as a massive time-saver!), then that would explain it. Sammi Brie (she/her • t • c) 23:08, 25 August 2022 (UTC)Reply
Geographical place of publication; generally not wikilinked; omit when the name of the work includes the publication place, for example, The Boston Globe, The Times of India. Displays after the title. If the name of the publication place changed over time, use the name as stated in the publication or used at the time of the source's publication.
So the template documentation reflects traditional citation guidance from other style guides, which as mentioned, is to omit the place of publication (usually understood to the city) for a newspaper if it's already contained in the publication name. Some people will list a city if the paper name only contains a state or country name, like the Arizona Republic, but well known examples like The Wall Street Journal, USA Today, or The Times of India wouldn't need them.
Also, some papers have changed if they include their city or not: The Blade used to be the Toledo Blade, and the Lansing State Journal had previously been just The State Journal. A paper may have moved, as I think The Times of Northwest Indiana did. That's what that last part means. Newspapers.com may or may not reflect reflect such changes. That's why editors have to double check what an automated tool generates against the actual source and customize it as necessary. Imzadi 1979→23:28, 25 August 2022 (UTC)Reply
A good optional practice with citations is to add the OCLC number for entries whenever possible. (Also ISBNs for books and some maps or ISSNs for periodicals. Note, not all sources have an ISBN or ISSN, but if it's in a library someplace, it should have an OCLC number.) For The Parsons Sun, it has an OCLC of 233144714 according to WorldCat.org. So while the footnotes link to clippings on Newspapers.com, should that website ever fail, a link to the OCLC would enable readers to locate archives of the paper in libraries as an additional means of verification. Listing such an ID number also serves as a discreet and non-redundant form of disambiguation.
Map citations should list grid references whenever possible. You shouldn't list a citation to a book without a page number to tell the reader where in that book you consulted, and so you shouldn't cite a map without telling a reader where on the map you found your information. (Of course, not all maps have grid references.)
@Imzadi1979: Hi, I fixed almost everything. Let me know what you think of the route description section. Also I looked again to find when the tracks were removed, but can't find anything, maybe you know a trick that I don't yet and can find it on newspapers.com? I would appreciate it if you could find it because I would like to add it. Let me know anything that needs to be tweaked. Thanks -420Traveler (talk) 15:15, 26 August 2022 (UTC)Reply
Searching under "rail abandonment" and including the railroad name Missouri Pacific brought up some hits when filtered down to Labette County and using a time frame starting in 1986 (when the crossing was set for improvement) through 2007 (when you've noted that the crossing had been removed by). From there, using details found in the earlier articles, I found more articles later. I've got this timeline so far:
November 1986, Union Pacific, owner of Missouri Pacific, was looking to purchase the Katy Railroad and then abandon several lines after the merger including the Coffeyville–Chetopa line which ran through Edna.
February 1987, Missouri Pacific filed abandonment requests for a number of rail lines, but they were trying to sell the Coffeyville–Chetopa line and didn't include it.
March 1987, the intended purchaser of the line is identified in an article as Watco, Inc. of Coffeyville.
December 1995, an article talks about a Santa train stopping in Edna, so we know that the line was there at least that long. After that, the trail goes cold on Newspapers.com. Google News Archive has nothing. There are only five results for the railroad in NewspaperArchive.com after 1995, none of which help.
I just checked the KDOT Historic State Maps, and the rail line in question was still marked on the 1997–1998 edition, but gone on the 1999–2000 edition. So that line was abandoned in either 1997 or 1998. Using that as a reference point, I just found an article about a proposed rail trail project on that ROW in May 1997 that says the railroad planned to abandon the line. An article on NewspaperArchive.com from May 1, 1997, also discussed the trail proposal and said that the line was to be abandoned that month. (I found a similar article in NewspaperArchive.com from the same month about an abandonment in Missouri that corresponds to part of the line that extended into that state with a September 1996 filing.)
b (citations to reliable sources): 
b (appropriate use with suitable captions): 