More Severance Michigan Connections
In this post I describe two Michigan connections in Severance that I haven't seen anyone else on the web notice just yet.

Having gone down quite a rabbit hole between rewatching certain episodes of Severance and browsing Reddits and fan wikis, there is no doubt in my mind that the fictional region of "PE" is located in Michigan's Upper Peninsula.
The show provides ample evidence for this, ranging from very clear clues to circumstantial evidence that can't stand alone but contributes to a compelling Michigan case.
The "Kier Invites You to Drink of His Water" painting, for example, clearly shows the Great Lakes, though with a substantially lower water level than they have today — possibly hinting that the Lumon corporation/Eagan family somehow control a large swath of the area's natural resources. Characters at various points make offhand references to Grand Rapids and Milwaukee. A character introduced mid-season 2 enjoys whistling the Gordon Lightfoot song, The Wreck of the Edmund Fitzgerald, about a famous Lake Superior shipwreck that took place quite near Michigan's Upper Peninsula ("The searchers all say they'd have made Whitefish Bay / If they'd put fifteen more miles behind her").
More circumstantial evidence includes, for example, that S02E04's ORTBO takes place in terrain (and a climate) that quite nicely matches with what you'd find in the UP, either in the Porcupine Mountains or near Marquette or Copper Harbor. And — this one is really circumstantial — cars in Kier, PE do not have front license plates. Michigan doesn't require front plates; Wisconsin and Minnesota do.
Anyway. S02E06 included not one but two plausible Michigan connections that I wanted to share.
Gull Harbor Road

In this episode we're reminded that Burt G. lives on "Gull Harbor Road." Other employees in this scene have addresses on more generic street names (Michigan has several Stout Roads, and at least one Magnolia Lane, as I'm sure most other states do). And to be fair, other states have Gull Harbor Roads too.
But. Lake Michigan's Beaver Island, a vacation destination for full-blooded Michiganders near the Upper Peninsula and the Mackinac Bridge, has a Gull Harbor Drive:


To be fair, Beaver Island is not part of the UP. But the street name, taken in connection with all the other evidence, hints that the show's story has a strong Michigan connection.
From the same scene in S02E06, take a look at this regional road map:

Michiganders will immediately notice not just the presence of a large suspension bridge, but the distinctive color scheme of the Mackinac Bridge. Compare to this aerial photo of the Mackinac Bridge:

Photo by Justin Billau - Flickr: Mackinac Bridge, CC BY 2.0, Link
This aerial photo is shot looking north toward the Upper Peninsula. The geography is different than that shown in the map's photo, to be sure. (Though the aerial perspective makes the landscape look much flatter than it is; the St. Ignace area is hillier than it appears here!) But I think it's another clear nod to the show taking place in a fictionalized version of the UP.
Finally, there is somewhat of a tradition of companies extracting natural resources from the UP (primarily logging and mining; see Wikipedia) and obscenely wealthy businessmen and their heirs buying and selling vast amounts of land up there — see, e.g. this recent news or the second paragraph of this 2022 New Yorker piece, excerpted here:
The cabin was built in the early nineteen-twenties by Louis G. Kaufman, a banker and businessman who helped finance the construction of the Empire State Building. He came up with the name Granot Loma by combining letters from the names of his children. Kaufman died in 1942, and more than four decades later Baldwin bought Granot Loma—and the five thousand acres on which it sits—for 4.25 million dollars.
Given this history in the Upper Peninsula, IMO it is quite plausible that, in the Severance universe, the Eagan family has managed to establish some sort of independent state up there.
Perhaps in this alternate timeline, the family had something to do with the Toledo War, which ended in 1836 when Michigan gave up the Toledo Strip in exchange for the western three-quarters of the Upper Peninsula. Kier Eagan was born in 1841; maybe his parents or grandparents were somehow involved in the conflict and were able to benefit from it, creating a pseudo-state in part of that area?
We may never find out definitively, but until the show proves otherwise, this timeline is my headcanon.
(Lake Superior is notoriously frigid; are the name Cold Harbor and the doctor's whistling Edmund Fitzgerald a nod in that direction)?