RE: Logbook entry: McSweeney's
Virtually all of the "hot dog stands" in this area, where Michigan Red Hots are regional a specialty, use this style bun. In addition to McSweeney's some others include Clare & Carl's two locations; Gus' Red Hots (both reviewed or logged on roadfood.com); and Ronnie's Michigans. Many other places serve Michigan Hot Dogs as part of their larger menus and they also all use this style bun.
What I have come to call the Michigan Belt" includes northeatern New York, generally from Ticonderoga to the Canadian Border and West to perhaps Malone and Tupper Lake. Also included is a small portion of northwestern Vermont along Lake Champlain from Burlington north.
There was a "bun crisis" hereabouts as few years ago. A local(actually regional) bakery, Boyuea/Fassetts, was pretty much the sole producer of this style bun. When this family-owned business sold out and their Plattsburgh bakery was shutdown, the pans that the buns were baked in evidently got thrown away. The buns currently used by everyone are similar but somewhat smaller.
An unrelated comment about Michigan Hot Dogs: While a "Michigan with" (onions, that is) is most common; obviously many times one orders a "Michigan without", The whole taste is noticeably different, but it allows the diner to more fully savor the flavor of the sauce IMHO.
Probably more than you wanted to know.