Also like the other person who commented, had never heard of this root beer either. Wish I could try it, though. As for Hire's, weirdly enough I'd never once seen this root beer, anywhere. Now I'm going to do some quick online research, to see what I find out about Hire's Root Beer.
ETA that I did find 3 articles with more info. Hire's was originally started in Philadelphia, btw. Info:
https://en.wikipedia.org/wiki/Hires_Root_Beer
https://www.drpeppersnapplegroup.com/brands/hires
https://stuffnobodycaresabout.com/2011/08/22/killing-a-product-why-you-cant-find-hires-root-beer/ (there are some good leads on possible stores that sell it, if you read the comments here. some comments here had success finding it in certain stores in Iowa and Minnesota. and one commenter even said they had success at Jungle Jim's, in Cincinnati. also, ABSOLUTELY annoying as crap that Dr. Pepper/Snapple had quietly been greatly slowing down production for like 10 years, in favor of A&W(sigh))
Let me add that there is NO JUSTIFIED reason in fregging hell to downvote this comment! And whoever did, unnecessarily did that with no proper justification at all there. It was NOT like I was namecalling anyone there, or doing something else inappropriate where a downvote would've been justified. I can't help it that the 3rd article, unfortunately didn't come up with a lot of leads for places in Illinois where you could buy Hire's Root Beer at. If you ACTUALLY spent time to read that 3rd linked article, there is no doubt that fewer bottlers making Hire's for Dr. Pepper/Snapple, is why it's becoming so DAMNED hard to find in so many states. And sadly the trend of less Hire's Root Beer being made(at the unnecessary expense of them too heavily promoting A&W), has been going on for about 10 years now. It seems like one of the last bottlers still making this sometimes is able to supply Minnesota and Iowa stores with it. Why that bottler doesn't distribute more of it to Illinois and perhaps Wisconsin too, I have no idea.
Don't forget if you're really, really desperate, that you always could probably buy some online. Say like on eBay or Amazon. If the OP or anyone else manages to find Hire's anywhere, please post what you think of their root beer! I've always been a root beer fan, and wouldn't mind trying Hire's IF by some random chance I ever find it somewhere. And thinking back to years ago when Joey's Soda Shop was around on Montrose east of Damen, unfortunately I don't ever recall seeing Hire's sold there ever on all of my visits there during the years it was in operation in the late 2000s and early 2010s. Heck, even both locations(Glenlake/Broadway, and Lunt/Western) of Lickity Split Custard, have never once sold Hire's Root Beer either. So honestly, I really wish I could give you a lead of where to find it in the Chicago area, but sadly for now I can't.
If ANYONE ever manages to find Hire's sold anywhere in the Chicago area, PLEASE do make another comment within this thread before it archives 5 months from now, or create a new thread here to say where you found Hire's at. Since I'd love to try Hire's, myself! I think only once ever in my life did I see Hire's sold anywhere, and this was when I was on vacation somewhere in one of the Mid-Atlantic or more eastern Southern states when I was a kid. Really wish I could've tried it those many years ago, but sadly didn't.
Online links to purchase Hire's, that I found when I did more searching on Google and Bing(and special thanks to u/8keltic8 , since now I'd like to try Hire's at some future point myself. maybe AFTER I first purchase online some more Foxon Park soda before I get to Hire's, that's for sure!):
https://www.sodafinder.com/products/hires-root-beer (thanks Bing, price quoted here is slightly cheaper than Amazon btw)
https://www.amazon.com/Hires-Root-Beer-pack-12-ounces/dp/B004743S5O (more thanks to Bing)
https://www.walmart.com/ip/Hires-The-Original-Root-Beer-12-Fl-Oz-12-Count/196579658 (also from Bing, note their price is sadly worser than both Sodafinder and Amazon)
https://www.ebay.com/itm/114098378419 (from Bing, similar to the price on Amazon)
https://www.foodservicedirect.com/hires-root-beer-12-count-per-pack-2-per-case-22998837.html?gclid=Cj0KCQiA7aPyBRChARIsAJfWCgISDjX5meumaAhK_8p9yvHiNuTkL75XCK6OwhMi0FHNkp8-lX_4rKUaAgoeEALw_wcB (from Google Shopping, and CHEAPEST price I found by far! winner winner chicken dinner)