A Black Run in Colorado and a Black Run in Austria Are Not the Same Thing. The Maps Prove It.

You have skied blues at home and you are booking a week abroad. It is a reasonable assumption that a blue is a blue.

It is not. We hold the difficulty grade of every marked run at 2,888 ski areas, and the grades do not survive the flight.

The same word, four times as often

Share of marked runs graded advanced or harder, by country:

	Ski areas	Beginner	Intermediate	Advanced or harder
Canada	118	25%	34%	41%
United States	364	23%	37%	39%
Japan	184	49%	31%	20%
Slovakia	27	56%	35%	9%
Italy	151	47%	43%	10%
Austria	188	52%	39%	9%
Switzerland	168	53%	38%	9%
Germany	39	53%	38%	9%
Sweden	34	65%	24%	11%
Norway	52	71%	20%	9%
France	188	66%	26%	8%
Czechia	27	67%	27%	5%

Nobody believes the Rockies are four times steeper than the Alps. Chamonix, Zermatt and St. Anton are not gentle mountains. What the table shows is that the word “advanced” is being handed out on different terms.

Look at the very top of the scale and the gap widens further:

	Advanced	Expert
United States	29%	11%
Canada	29%	11%
Japan	19%	1%
Italy	10%	0%
Austria	9%	0%
Switzerland	9%	0%
France	8%	0%

One American run in nine is graded expert. In the Alps the grade is barely used at all. Not because there is nothing hard there — because European grading effectively stops at black, and everything beyond it is left off the piste map entirely.

The two systems are answering different questions

Europe grades the piste: a marked, patrolled, groomed-or-groomable trail, coloured by how steep it is. Anything steeper or wilder is not a harder piste — it is not a piste. It leaves the map and becomes off-piste, which is ungraded and unpatrolled.

North America grades the terrain: everything inside the boundary is on the map, including trees, chutes and bowls that in Europe would simply not be drawn. Those need a grade, so the scale had to keep going — hence the double black diamond.

So a European black and an American black are not two opinions about the same slope. They are the last rung of two ladders of different length. Europe’s ladder ends where the groomer stops. America’s carries on past it.

Japan sits between them, and not by accident

Japan’s 20% is halfway between North America’s 39% and the Alps’ 9%. That is the arithmetic. The reason is more interesting.

Japanese ski areas mark tree runs and ungroomed zones on the map, the way North America does — so those runs need a grade. But Japan uses green, red and black, borrowed from the European three-colour idea. The result is a North American amount of terrain squeezed into a European number of rungs, which pushes runs up the scale.

The expert figure gives it away: 1% in Japan against 11% in North America. Japan has the terrain but not the fourth rung to put it on.

What to actually do about it

Coming from North America to the Alps: do not read a European black as a black diamond. It is closer to a steep blue-black at home. But treat the edge of the piste map as a real edge — in Europe, one step off the marked run puts you in unpatrolled avalanche terrain with no signage. In the United States, that same step often keeps you inside the boundary.

Coming from Europe to North America: expect the map to be busier and the grades to look harsher. A single black diamond is frequently a European red. The grade you should respect is the double diamond, which has no European equivalent on the map at all.

Either way, coming to Japan: the grades will read soft and the trees will not be. Half of Japan’s marked runs are beginner runs, so the map looks gentle. What is not on the map is that Japanese tree skiing sits in the deepest snow in this table, and the rules about where you may enter it differ from one ski area to the next.

And in all three: ignore the ratio when comparing resorts across borders. “40% advanced terrain” is a fact about the country’s grading habits before it is a fact about the mountain.

How this was measured

Grades come from the piste:difficulty tag on OpenStreetMap, counted for every marked downhill run within a radius of each ski area’s centre that scales with its mapped size. OpenStreetMap uses the five European grades — novice, easy, intermediate, advanced, expert — everywhere, so North American maps are translated into that scale by whoever drew them. That translation is itself part of what we are measuring, and it is done by volunteers rather than by the resorts.

Two things follow. First, these are not the resorts’ own published percentages and will not match them. Second, a country’s figure reflects both its terrain and its mapping conventions, which is precisely the point of the article — but it means you should not read a two- or three-point difference between neighbouring countries as meaningful. The gaps worth noticing here are 39% against 9%, and 11% against 0%.

Ski areas with fewer than ten marked runs are excluded, as are countries with fewer than ten qualifying ski areas or fewer than fifty graded runs in total. Runs with no difficulty tag are left out of the percentages rather than assumed.