Above 8,000 feet, where the tables stop

The gap, stated exactly

Dial-gauge process tables in the 2015 USDA guide have four altitude columns: 0–2,000 ft, 2,001–4,000 ft, 4,001–6,000 ft, and 6,001–8,000 ft [F-4.2]. The fourth is the last. Nothing follows it.

Boiling-water tables have four columns too, but the top one is open: 0–1,000 ft, 1,001–3,000 ft, 3,001–6,000 ft, and above 6,000 ft [F-4.2]. Weighted-gauge tables have two, and the top one is also open: 0–1,000 ft and above 1,000 ft [F-4.2].

So the honest headline has a qualifier in it, and the qualifier is the whole story: above 8,000 feet a dial-gauge canner has no USDA process, and a weighted gauge does [F-4.2].

I am being fussy about this on purpose. "The tables stop at 8,000 feet" is the version that circulates, and it is true of one table type out of three. A reader at nine thousand feet who believes the loose version thinks they have no tested option for anything, which is wrong and would push them towards guessing. A reader who knows the precise version knows that their weighted gauge and their boiling water canner are both covered as published, and only the dial gauge is not.

Why the gap exists, probably

The guide does not say, so what follows is inference and I will label it as mine rather than the guide's.

Altitude compensation in a pressure canner is done with pressure. The published pressure ceiling is 15 PSI: processes in excess of that are not recommended on new pressure canning equipment [F-4.3]. The top dial-gauge band already sits close to that ceiling for many foods.

So extending the table upward would mean either exceeding the guide's own stated ceiling, or running a new set of thermal process studies at elevations where relatively few people live. Neither is free. The result is a table that stops.

That is not the guide being careless. Notice what it did not do: it did not extrapolate a fifth column and print it. A document that declines to publish a number it has not tested is behaving correctly, even when the silence is inconvenient for the reader standing in Leadville.

Where the numbers people actually use come from

Somebody at nine thousand feet who searches for an answer will find one. It is worth knowing what they have found.

Ball publishes a high-altitude chart with an 8,001–10,000 ft band, giving 15 lb for both dial and weighted gauges and a 20-minute increase for water bath processing at that band. The page prints no source for any of it [F-4.4].

Healthy Canning is the only site found that names an origin, and it attributes the above-8,000 figures to the Bernardin Guide to Home Preserving, Bernardin Ltd., Toronto, 2013, page 12 [F-4.4]. Bernardin is Newell's Canadian home-canning brand, and Newell owns Ball.

Follow that through and the picture is unusual enough to state carefully. Figures circulate in American kitchens with the authority of the USDA tables they sit beside. They are not in the USDA guide [F-4.2]. On the US manufacturer chart they carry no citation [F-4.4]. The single public attribution points to a Canadian commercial guide published by the same corporate family [F-4.4].

And here is where this site stops. Nobody here has read page 12 of the 2013 Bernardin guide. It is a print book. So the printable claim is that Healthy Canning attributes the figures there — not what Bernardin says, and not whether the attribution is correct.

Somebody with a copy on their shelf could close that loop in a minute. Until somebody does, the trail ends where the evidence ends.

What to do instead

Three options, in the order I would take them.

Use a weighted gauge. Its top band is open-ended above 1,000 ft [F-4.2], which means the tested tables cover your elevation without anybody having to extrapolate anything. At high elevation this turns the gauge decision from a preference into a practical advantage: dial gauge or weighted gauge.

Ask your state Extension service. Colorado, Wyoming and Utah between them hold most of the US population living above the top USDA dial-gauge band, and their Extension services publish high-altitude preservation guidance and answer questions from residents. That is a better source than any national page, including this one, because they know what elevation your county actually sits at. The links are above, and Ask Extension will route a question to your own state if your service is elsewhere.

Know your elevation to begin with. Not your town's — your kitchen's. The guide declines to publish a lookup precisely because terrain varies within a county [F-4.5], and NCHFP runs a page for finding yours. The full version of that argument is on find your altitude first.

The general lesson, which is bigger than altitude

This page is about one closed column on one kind of table. The pattern is everywhere in this subject.

A tested source stops. The gap is real and the reader still has a kitchen and a harvest. Somebody fills the gap with a number. The number acquires the visual authority of the tables it is printed next to, and after a few years it is simply what everybody knows.

The defence is not scepticism, which is exhausting and mostly makes people trust nothing. It is one habit: when you find a figure, look for the source printed beside it. On the USDA tables there is a document, a revision year and a page. On the chart with the 8,001–10,000 ft band, there is nothing [F-4.4].

That difference is visible in two seconds, and it is most of what this site is trying to teach.