Because dictators killing people through executions, starvation, deliberate mismanagement of resources, incompetence, torture, and brutal prison conditions is sadly prevalent throughout history. What is unique about the Holocaust is the deliberate, industrialised and highly organised genocide of a specific people. There has never been a dictator who had an entire ethnic group first individually entered into a filing system, then rounded up and transported to a dedicated extermination centre, to have them killed upon arrival and burned or buried within hours, without regard to age or gender.

Maybe my perspective as a Canadian highschool history teacher could be helpful here. We have one compulsory history course in Ontario (largest province in Canada) and it's Grade 10 Canadian History. This course is suppose to track Canadian History and the development of "Canadian Identity" from WW1 through to the present day, but we still (almost always) spend a unit on the Holocaust.

Why?

Well first we have to talk about it. Unlike other genocides that commenters have been discussing here I can't skip over the Holocaust. Mao's GLF, Stalin's Purges, Pol Pot's Killing Fields... all of these don't directly intersect with Canada's identity narrative and popular narratives around WW2. WW2 is going to be taught and Canada's involvement is going to be taught, so that means we have to deal with the rise of Nazism and differentiate between the revisionist causes and the grounded historical causes. Canada did not go to war because of Hitler's organized destruction of segments of his own populace. Canada went to war because of a complicated history of Empire and Culture, and nation level aggression by Germany. I have to teach this because I need my students to know that Canada turned away [fleeing Jewish refugees] (http://en.wikipedia.org/wiki/MS_St._Louis). I need my students to know that the Holocaust wasn't well known until after the war. I need my students to understand the difference between war for "King and Country" and war to protect a people, because Canada has (arguably) engaged in both and to differenciate WW2 I need to teach the Holocaust from start to finish.

Second, because I have to talk about it, I have to teach it well. If I bring up something like the Holocaust, something that so many of my students (both Jewish and others) have a personal familial connection to, I have to do it justice. I have to make sure that my students understand the horror, the organization and the scale of it. I've had Holocaust denier students, I've had students who's Grandparents bore tattoos and I've had students who had no idea that such a thing ever happened. If I don't address it in depth and lay a baseline of historical fact how can these students discuss Canada's peacekeeping missions in the late 20th century that happened in light of the Holocaust?

Third, the Holocaust is staggering. Sane people understand this and thus we can use it as a touchstone, a reference for other genocide. The UN's ideas of genocide only come out as reaction to the Holocaust so my students need to know about it. I can't talk about the UN's inaction in Rwanda if my students don't know what the standard of "genocide" that had to be met before international action would be taken. Canada had a large role in that mission and it is part of our narrative, so to address that I need my student to understand what genocide is and ... conveniently I'll have already covered one.

Lots of great answers here, but I'd like to add something. The fact that the Holocaust is drilled into our education system is due in part to the strong animosity that still targets the minorities impacted by it (Jews, Gypsies, homosexuals, etc). There is a strong incentive for these groups to find and encourage education about this horrific event because it will reduce the chances of it happening again.

The Southern Poverty Law Center has an interesting essay on the motivations behind Holocaust denial: http://www.splcenter.org/get-informed/intelligence-files/ideology/holocaust-denial/essay-the-holocaust-denial-movement

The impact it had on popular culture, without a doubt. Here is a list of holocaust-related movies. There's more than 100. In a cursory search on Google, I came up with one film about Holmodor and four about Stalin. It's an imperfect metric, but you get some sense of the relative importance society places on these things.

In my personal experience what you teach in history (era, events, etc) is less important that sparking an interest in the students whilst imparting skills of critical thinking, research, source analysis, historiography, etc. It is a lot easier to do this when there is some existing reference points around which the students can operate. Or something which students are motivated to learn about. On another level, students may be able to connect more readily with something that carries a personal connection - either through personal links to a family member who fought in the Second World War or to the general national history of said time. Personal connections to Mao's China or Stalin's Russia are less common in most Western countries.

As to reasons for a focus on the Holocaust within the English-speaking world? The fact that Nazi Germany was an enemy in WW2 rather than an ally, the revelation of the Holocaust in such a shocking and public way, the capture of Nazi documents, the Nuremberg trials, a convenient 'bad guy' in the Nazis, etc, etc, etc.

Regardless of the reasons, it is a central part of a general Western culture. Not a particularly pleasant part, but central nonetheless. It seems perfectly natural for History education to reflect the interests of society.

A lot of people have brought up some really good points, but I'd also like to bring up the fact that a lot of Holocaust commemoration is done by the Jews themselves. The Jews have a long history of persecution, and after the Holocaust their mantra became "never again". Thus, countless Jewish organizations have used their resources or have been created in order to spread knowledge and awareness of anti-Semitism, to commemorate the people who lost their lives in the Holocaust, and to ensure that the Jews are never turned on by their home countries again. There's a concept among Jews that our revenge against the Nazis is having kids and then educating the next generation. If you would speak to a Holocaust survivor they will tell you about all of their kids and grandkids, and how because one person survived, countless other generations also had the potential to lead Jewish lives and essentially step all over the Nazis' goal.

I should preface this by saying that I would tend to agree with the point /u/acqua_panna made in their response to this question - that it's an almost impossible question to answer with the kind of factual rigor required by this sub. That being said, I think /u/estherke provided the most fundamental explanation for the (American, at least) education system focusing on the Holocaust at the expense of other atrocities, but, on top of that, I think political climate & demographic data have a lot to do with it, as well.

Israel is and has been a staunch US ally since the country came into being, while (to address the two other contemporary atrocities you mention) relations with China and USSR/Russia in the post-war era have been, at best, icy, and at worst, openly hostile. Second, almost half of the world's Jewish population live in the United States, as many as 8 million (depending on your definition), which is greater than the combined population of both Russians and Chinese living in the US.

All other factors aside, I think this combination of sympathetic audience/political climate and large number of people with an active interest in keeping the lessons of the Holocaust alive do a decent job of explaining why it's maintained its place in the education system at the expense of other genocides/atrocities.

Is this really a question for historians? Maybe for a philosopher of history, a sociologist of history or a particularly reflective historian would be concerned with such a question, but I think it lies outside the scope of history proper. The question is essentially about an aspect of present day education or more generally about present day culture, which would be of more interest to sociologists, social psychologists or anthropologists rather than historians in my opinion.

All very good answers that I'm seeing here, I just want to add how this question was answered in my modern European history course in college.

Before World War One there was a European myth of civilization. Propaganda might say that the central powers were eating babies, but it was just propaganda. At the end of the world the western world could still tell itself that it was the bastion of law and order. Nations might fight, which was certainly a shock to the system, but each power was still civilized.

When the Holocaust became known it tore apart the narrative of progress in civilization. It completely changed how the western world viewed itself. Yeah, it was the bad guys who did it, but they were supposed to be a great power, a nation on the world stage, a civilized people. It wasn't so much that it happened (though I'd argue that it being the first well known genocide of this scale), but that it was otherwise civilized and racially acceptable people who did it.

I'm reminded of the novel The Chosen by Chaim Potok. It tells the story of a Jewish boy in NYC during the end of the war. The Jewish community can't believe the news when it becomes known. Jews knew they were persecuted, that wasn't surprising. Everyone knew that. But no one could imagine nice law abiding prosperous Whites doing something like this.

The whole concept of scientific racism, already dying, was beaten to a pulp. Here is (in the mind of western powers in 1946) the worst thing that anybody has ever done. And they were White. The Holocaust necessitated a compete reconceptualization of what it meant to be civilized, White, human.

And it coincided with the US dropping the bomb. That event also forced a rethinking of what humanity was capable of. So the end of WWII became a graveyard of old romantic ideals (on top of being a literal graveyard).

This is an interesting question because I think it has many, many answers. The obvious one is that the Holocaust happened during the largest armed conflict ever recorded and was so utterly deliberate and vast to induce awe-inspiring disgust, fear, and tragedy. Many will argue that the industrialized nature of the Holocaust makes it a unique horror to this day. I'm not really qualify to say if it isn't. It probably is.

I'm much more interested in other interpretations because of my own biases. For me the Holocaust was the culmination of European, and North American ideas about race and colonialism and empire. The Jews in central Europe, and I do not make this connection lightly but to make the point that the ideas that gave rise to the Holocaust weren't foreign to the rest of the Western world, could have been Black people of the USA, or First Nations in Canada, or maybe even the Indians in the British Empire. I think seeing these ideas played out in full in Europe, the supposed heart of civilization, was sobering for many of the victors. This is what those ideals look like, cold, precise genocide. They could no longer ignore the human cost.

And I'm also interested in one more answer, one I think is cynical to the extreme yet I can't rule out as non-plausible. The Holocaust makes the victors look good. I think this probably most prevalent in the USA which I would argue has used it's global goodwill after WW2 to justify various 'police actions' and wars. They aren't taught about the Holodomor, or the Great Leap Forward, of Khmer Rouge, or Rwanda, because none of those things can fit into the jingoistic moralistically simply story of 'Us good, Them bad'. Some are even clearly rooted in American and European imperialism, like Khmer Rouge and Rwanda respectfully.

I think all these answer are correct in some fashion. I think as far removed as we are from the Holocaust today means we can now start questioning the prevalence of it the Western world collective social consciousness and come away with many answers.

Stalin and Mao were bad, don't get me wrong, but for the most part the tragedies were not direct in the same way as Hitlers Holocaust.

The majority of the 40 million killed under Mao were killed due to starvation and bad management of food resources. The famine would have happened regardless, but Maos policies made it worse, however for the most part he at least had good intentions for his people.

Stalin was a bit worse than Mao, he forcefully put millions to death in WW2, however once again, he did not necessarily 'want' them to die, but he needed soldiers desperately and was willing to use as many of his own people to fight in the war. Holomdor was a famine, while it was caused deliberately by Stalin to punish the Ukrainians, it was still mostly indirect.

Even the biggest comparison to the Nazi's, the Japanese, were not even remotely as horrific or murderous. Most of the Chinese that were killed were killed due to the fact that China was already in a state of civil war when Japan invaded. The estimated Chinese that died was around 22 million, however the majority of those deaths were due to war related famine or infighting among the Chinese. Japan was awful, don't get me wrong, but once again most of the deaths in that area were indirect.

Now, the reason why the Holocaust is so special, so remembered and studied, is because of its uniqueness. There was no previous famine among the Jews, there was no civil war that was already happening, the Jews, for the most part, weren't even armed. They were just civilians, wealthy ones at that, and all of the hatred and anger at them resulted in them literally being put on trains and gassed. 6 million of them, along with 2 million Poles, and 3.5 million Russians, were DIRECTLY killed by the Germans in the camps. I did an internship at the Jewish Holocaust Museum in Battery Park, NYC, and the horror of the Holocaust is unmatched anywhere in human history. A lot of why this is is because the Jews really were innocent, they were not rebels fighting against the Germans, they were not thieves or criminals that drained society, they were systematically executed based on a lie that Hitler told his people. In Holomdor, the reasons why Stalin implemented the famine were because the Ukrainians were revolting. In the Holocaust, the reason why Hitler slaughtered the Jews was because he simply did not like them.