The Grand Hotel on Mackinac Island tells you its front porch is 660 feet long and the longest in the world. The two federal documents that actually measured it say 627 and 628 feet. And no organization anywhere certifies the record.
The porch is real and it is enormous. The claim bolted onto it does not survive a records check, and the reason why turns out to be more interesting than the superlative.
Three credentialed sources, three different numbers
The National Historic Landmark nomination for Grand Hotel, prepared by National Park Service architectural historian Carolyn Pitts and dated February 14, 1989, describes the enormous deep verandah “which is 628 feet long.” The separate Mackinac Island NHL nomination, also an NPS document, gives 627 feet.
The Historical Society of Michigan, in a profile written by Katie Mallory, then curator of education for Mackinac State Historic Parks, says 680 feet. The hotel’s own press page says 660. MyNorth reported the original 1887 porch at 440 feet.
The published figures run from 440 to 680 feet. That is a 240-foot spread on one structure, and the two most authoritative documents in the pile are the two that disagree with the hotel.
Nobody keeps this record
Guinness World Records has no category for longest porch, longest veranda, or longest balcony, and Grand Hotel appears nowhere in its records. The nearest thing Guinness actually certifies is the longest covered wooden corridor, the Long Corridor at the Summer Palace in Beijing, at 2,388 feet.
The 1958 Michigan Historical Commission marker on the grounds calls it longest in the world as well. State markers are not adjudications. There is no register, no measurement standard, and no rival claim anyone has filed, which is a very different thing from having won a contest.
The porch that earned the claim was a third shorter
Here is the part no coverage mentions. The Mackinac Island NHL nomination states plainly that “additions in 1897 and 1912 increased the length by half.”
Run the arithmetic backward from 627 feet and the original 1887 porch lands around 418, which lines up with MyNorth’s 440. The world’s longest porch printed on linen postcards in the 1930s was already a porch that had been extended twice. What opened in 1887 was roughly two thirds of what is standing today.
And it was not built in 93 days
The 93-day construction figure is repeated everywhere. It is not in the NPS nomination, not in the Historical Society of Michigan profile, and not on the historical marker.
The NPS nomination says builder Charles W. Caskey, working 300 men through 1.5 million feet of lumber, “finished the job in just over three months.” The Historical Society of Michigan says four months. Construction began in March 1887 and the hotel opened July 10, which is 131 days. Only an April 8 start yields exactly 93.
What is actually documented
Opened July 10, 1887. Built of Michigan white pine hauled across the ice the winter before. Built by Charles W. Caskey of Allegan with his brother-in-law Alphonse Howe, financed by the Grand Rapids and Indiana and Michigan Central railroads and the Detroit and Cleveland Navigation Company. Listed on the National Register of Historic Places on May 5, 1972, and designated a National Historic Landmark in 1989.
Every one of those sits in the Michigan Historical Commission marker or the NPS nomination, and every one is checkable in an afternoon. The porch length is the only number about this building that nobody can pin down.
The person who could close the gap is Bob Tagatz, the hotel’s resident historian. If 660 counts something the federal surveyors left out, he is the one who would know.
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Sources, credits, and reporting details
Sources & accountability
How this story was reported
Editorial methodArchival synthesis
Last verifiedSep. 9, 2026
Corrections statusNo material correction note is recorded on this article.
AI assistanceResearched and drafted with AI tools. Reviewed and approved by editor Keegan O’Brien.
Verification note: Ledger establishes that the two NPS National Historic Landmark nominations measure the Grand Hotel porch at 628 ft (Grand Hotel NHL, Carolyn Pitts, 2/14/89) and 627 ft (Mackinac Island NHL), against 660 ft on the hotel's own press page, 680 ft in the Historical Society of Michigan profile and 440 ft (original 1887 porch) in MyNorth; that Guinness certifies only a 'longest covered wooden corridor' (Long Corridor, 2,388 ft) and nothing for porches; and that the '93 days' figure traces to secondary coverage (MyNorth) while the NPS nomination says 'just over three months' and HSM says four months. The article deliberately does not assert any true porch length and does not claim any body has certified the world record.
Primary sources
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National Historic Landmark Nomination: Grand Hotel, Mackinac Island (NRHP ref. 72000637) — National Park Service, U.S. Department of the Interior (NPGallery)
Published Feb. 14, 1989. Accessed Sep. 9, 2026.
Text transcription of the NHL nomination form on NPGallery. The July 10 opening date is not in this document (it is on the 1958 state marker).
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National Historic Landmark Nomination: Mackinac Island (NPS Form 10-900) — National Park Service, U.S. Department of the Interior (NPGallery)
Accessed Sep. 9, 2026.
The 627-foot figure attributed to this document in the article was not surfaced in the fetched excerpt; the 1897/1912 'increased the length by half' sentence was confirmed verbatim. Editor should confirm the 627 ft figure in the PDF.
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Grand Hotel Facts (Press & Media) — Grand Hotel, Mackinac Island
Accessed Sep. 9, 2026.
Page references the 2026 season (140th season, opening April 24, 2026). It does not itself use the phrase 'longest porch'.
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Michigan Profile: Meet Charles Caskey, A Grand Builder — Historical Society of Michigan
Accessed Sep. 9, 2026.
No publication date shown on page.
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Grand Hotel Historical Marker (Michigan Historical Commission, 1958) — Historical Marker Database (hmdb.org), transcribing Michigan Historical Commission marker
Accessed Sep. 9, 2026.
Marker text transcribed by hmdb.org; the marker itself is the primary source. Marker does not name Caskey.
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Longest covered wooden corridor — Guinness World Records
Accessed Sep. 9, 2026.
Absence of a porch category is an argument from silence in Guinness's public records database; the page fetched confirms the corridor record only.
Additional reporting
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Behind the Scenes of Grand Hotel's Opening Day (It's Amazing) — MyNorth.com (Traverse Magazine), Emily Oakes
Published May. 19, 2020. Accessed Sep. 9, 2026.
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Grand Hotel (Mackinac Island) — Wikipedia
Accessed Sep. 9, 2026.
Used only for the exact NRHP/NHL dates; miplace.org (MI SHPO) confirms 1972 NRHP and 1989 NHL years.
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Grand Hotel | MiPlace (Michigan State Historic Preservation Office) — Michigan Economic Development Corporation / State Historic Preservation Office
Accessed Sep. 9, 2026.
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10 Questions with Bob Tagatz — Grand Hotel, Mackinac Island
Published May. 18, 2023. Accessed Sep. 9, 2026.
Photo and media credits
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Mackinac Island July 2010 01 (Grand Hotel).JPG (featured image) — Michael Barera, via Wikimedia Commons
Featured image record. Published Jul. 31, 2010. Accessed Sep. 9, 2026. CC BY-SA 4.0.
Supports: Featured image caption: 'Photo: Michael Barera (CC BY-SA 4.0), via Wikimedia Commons.'
Commons file identified Sept 9 2026 via the Commons API from the author credit and matching aspect ratio.
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