Use the column that matches where you live, not where the recipe came from. That’s the whole game.
Most decent canning recipes, give you a processing time table with four columns: 0-1,000 ft, 1,001-3,000 ft, 3,001-6,000 ft, and above 6,000 ft. Find your elevation band, find that column, use those times. Doesn’t matter that the recipe was written in Georgia and you’re in Wyoming .Your water boils at your kitchen, not at theirs.
If you don’t already know your band, the canning altitude calculator on this page will tell you in about five seconds. Type in your city, your ZIP or postal code, or let it use your location. You’ll get your band.

No. And I’ll tell you why, because “no” by itself doesn’t convince anybody.
Canning recipes are written assuming water boils at 212°F, that’s 100°C for all those using metric system. That’s sea level. The processing times in the table are calibrated to that temperature, because that’s what kills the microorganisms that would otherwise spoil the jar or, worse, make somebody sick.
Here’s the catch. Water doesn’t always boil at 212°F. The higher up you go, the lower the boiling point gets. Up at 6,000 feet e.g. Denver, water boils at 94°C, which is 201°F. That’s eleven degrees cooler. Eleven degrees doesn’t sound like much when you’re standing in your kitchen, but to a heat-resistant bacterium it’s the difference between dying and going dormant. The jar still seals. The food still looks fine. The microbes and bacteria are still in there.
This is why NCHFP isn’t squishy about altitude adjustment above 1,000 feet for water bath and steam canning. It’s a food safety requirement, not a suggestion. For pressure canning the rule is the same but the lever is different: instead of adding time, you add pressure, because a pressure canner can do what your boiling pot can’t, which is push the temperature back up. Either way, you adjust. Use the canning altitude calculator on this page to find your band before you start. It costs you five seconds and saves you a year of doubt about whether the jars on your shelf are safe.

If you’re using a water bath canner or a steam canner and if you’re above 1,000 feet, then yes, you need to do it for every single recipe, every single time. Doesn’t matter if it’s strawberry jam, dill pickles, crushed tomatoes, peach halves, or apple butter. Anything high-acid that you’re processing in boiling water needs the time adjustment. Higher up means longer processing. The recipe table tells you exactly how much longer.
If you’re using a pressure canner, you don’t add time. Instead, you add pressure. The processing time stays put; the PSI goes up. And here’s a useful thing to remember: with a pressure canner, the adjustment is the same whether you’re canning green beans or beef stew. The pressure correction doesn’t care what’s in the jar; it only cares what altitude you’re at.
If you’re not sure which kind of canner your recipe wants, look at the top of the recipe. It’ll say. Water bath canner, atmospheric steam canner, or pressure canner — those are your three options, and they don’t substitute for each other. Use the canning altitude calculator on this page to find your elevation band, then go to your recipe and either find the time column (for water bath or steam) or the pressure setting (for pressure canning) that matches.

The answer depends on which part of the city you’re standing in.
You’d be surprised how much elevation can change inside one set of city limits, especially in places that were built across hills and river valleys. The good news is that canning doesn’t need pinpoint accuracy. It needs your band: 0-1,000 ft, 1,001-3,000 ft, 3,001-6,000 ft, or above 6,000 ft. As long as you’re in the right band, the adjustment is the same whether you’re at 4,200 feet or 4,800 feet.
For a lot of cities, a city-level number is plenty. Take Denver as an example. Most of the city sits between 5,100 and 5,500 feet, all in the same band. So, you can call it “Denver” and be done. But take Pittsburgh, and the picture changes. Down in the river valleys you’re at maybe 700 feet, base band, no adjustment needed. Up in the hilltop neighborhoods you’re past 1,200 feet. Totally different band, different processing time. In a city like that, “Pittsburgh” isn’t precise enough. You need to know your part of Pittsburgh.
That’s what the canning altitude calculator on this page is for. If you let it use your GPS, it pulls your actual coordinates and looks up the elevation right where you’re standing. If you’d rather not, type in your ZIP or postal code  – that gets you within a few hundred feet, which is usually plenty. Type in just a city name and you’ll get the city’s average, which is fine in flat country and unreliable in hill country. Pick the level of precision your geography calls for.

No, and I want to be clear about why, because this is the question that gets people in trouble.
Tested canning times assume sea-level, that’s 100°C, 212°F. If you take those same times and use them at, say, 5,000 feet, your water tops out around 95°C and your food sits in a cooler bath for the same number of minutes the recipe specified. Cooler water for the same time means less heat delivered to whatever’s inside the jar. Less heat means the microbes and bacteria you were trying to kill may still be in there.
Here’s the part that catches people. The jar will still seal. The lid will pop down, the band will tighten up, the jar will look exactly like a properly processed jar. A sealed jar is not proof of safe processing. It’s just proof that the lid sealed. Sealing tells you the jar is airtight. It tells you nothing about whether the contents are safe to eat.
Use the canning altitude calculator on this page to find your band before you fire up the canner. It takes less time than for a water to simmer, and it tells you exactly which row or column of your recipe to follow.

Above 1,000 feet, for water bath canning and steam canning. That’s the line.
NCHFP set it there because below 1,000 feet, the boiling point doesn’t shift enough to matter -water still boils close enough to 212°F that the recipe times work. Above 1,000 feet, the boiling point starts dropping noticeably, and the recipe needs to compensate by running the jars longer. The Ball Blue Book uses the same threshold. So do the university extension services. There’s no controversy here.
Pressure canning is a little different. Standard processing pressure is 10 PSI in a weighted-gauge canner, and that holds up to 1,000 feet. Above 1,000 feet, weighted-gauge canners go up to 15 PSI. Dial-gauge canners step up in smaller increments, usually starting around 2,000 feet. Your canner manual will tell you exactly which adjustment applies.
The four standard canning altitude bands are the same ones you’ll see in every recipe table: 0-1,000 ft (no time adjustment for water bath or steam), 1,001-3,000 ft, 3,001-6,000 ft, and above 6,000 ft. Find your band, the canning altitude calculator on this page does it for you, and match it to whichever column of your recipe applies.

Easiest way is to use a canning altitude calculator that hands you the band directly, which is what the tool on this page does. Type in your location however you like – GPS, city name, ZIP or postal code – and it gives you your altitude in feet and meters along with your band. That’s the whole thing you need for canning. Done in five seconds.
If you’re the type who likes to verify, there are other ways. USGS topographic maps will give you your altitude to the nearest few feet. They’re free at usgs.gov, and they’re the gold standard if you want to be sure. Google Maps works too: right-click anywhere on the map and you’ll see the elevation pop up. Most smartphones have a compass or GPS app that shows altitude. And if you grew up around old paper maps, your state’s geological survey usually publishes elevation charts for the whole state.
For canning, though, you don’t need anything fancy. You don’t need to know whether you’re at 4,237 feet or 4,261 feet. You just need to know which band you’re in. Once you know your band, you’ve got everything you need to read your recipe correctly. And if you happen to live right on a band boundary, say, 990 feet, or 2,975 feet, round up to the next band.

Depends on what you’re canning, and the range goes from “annoying” to “dangerous.” Worth understanding the difference.
If you’re processing high-acid foods in a water bath, like jams, jellies, pickles, acidified tomatoes, fruit, and you skip the altitude adjustment, you’ll usually get spoilage. Mold growing on top of the jam, fermentation in the pickle jar, soft mushy texture, off smells, sometimes the lid pops loose a few months in. Annoying, wasteful, occasionally embarrassing if you gave jars away as gifts. But the high acid content keeps botulism out of the picture, so the jar isn’t dangerous so much as ruined.
Low-acid foods are a different conversation. Vegetables, meats, fish, soup, beans, anything that isn’t acidified, those have to be pressure canned, full stop, regardless of altitude. Water bath canning low-acid foods isn’t an altitude problem; it’s a category error. Under-processing low-acid foods is how you create Clostridium botulinum spores in a sealed, oxygen-free environment, which is the textbook recipe for botulism. So that’s the spectrum. Water bath at high altitude with no adjustment, on high-acid food: usually a wasted batch. Pressure canning skipped or shortchanged on low-acid food: a serious health risk you can’t see coming. The fix is the same in both cases – use the canning altitude calculator on this page, find your band, follow your recipe’s instructions for that band. It’s the difference between canning being a hobby and canning being a problem.