It seems like every 2-3 days we get somebody asking whether the Irish were held as slaves in America. It is such a common question that we have a FAQ about it. I'm curious as to why this is such a hot question and why it seems to be such a big topic on reddit.
In short, I suspect it originates out of the 'white slavery' myth that has been popular among neo-Nazis and their ilk for decades.
The origin of the modern, popularised myth we see people asking about here is rooted mainly in a book by Don Jordan and Michael Walsh called White Cargo: The Forgotten History of Britain's White Slaves in America, which - sadly - received a lot of uncritical press coverage at the time of its release (as too many awful popular history books do).
White Cargo isn't a completely terrible book; there are certainly worse books out there. But it is filled with highly confused, erratic narratives, a poor effort to engage critically with the source material and a determination from the outset to conflate white indentured servitude with racial slavery, which gives rise to a complete lack of appreciation for nuance and complexity.
From there, this review of the book appeared, which cherry picks from already seriously flawed work to create a polemic on the topic. It has, sadly, been shared about 350,000 times on social media in the last 7 years - not including all of the derivatives of it that have been made to spread this myth, or various uncritical media reports on the article. Trying to follow this up with searches for stuff like 'white slavery' tends to just lead you back to the same kind of content.
From there, there is the obvious difficulty that people trying to follow this thread in a bit more detail will run into the phenomenon of white indentured servitude, which they may then in turn associate as being synonymous with chattel slavery. There are other very flawed books out there as well that false 'experts' might recommend to people on the topic.
I suppose from there the story keeps circulating around and around again on social media; people see it, wonder about it and then wander over here to find out more.
/u/sowser has a pretty good explanation, but I'd also suggest that there is another reason it pops up: guilt and/or shame amongst the white population.
In the history of the Americas, the biggest atrocities are those perpetrated by white settlers against indigenous peoples, and slavery. Both of these are the result of Europeans, who also make up a majority of the population today in North America. The consequences of slavery and colonization are long term and are still seen today. However, whenever one of these things is brought up, the frequent response is "Get over it, it happened 200 years ago!" or "I never kept slaves! And you never were one!" and variants thereof. They are used in an attempt to remove a party from a position of responsibility for these acts. The concepts of Irish slavery pop up as a neat little excuse: "Well white people were slaves too, but you don't see us doing x, y, or z". It allows a white American to brush off or ignore (I hate the use of the following word, but it fits) privilege that you gain, merely by being white.
So, why is this needed to be ignored/brushed off? Because people like to think that they work hard for what they have. Generally, they do. But if someone works hard all their life, and end up as the CEO of a Fortune 500 company, and then get told that they're privileged because they're white, they might take offence because their hard work is being ignored. Instinctively they want to say, "No, I'm not privileged, I worked hard for this." In actuality, they are both privileged and hardworking. The two aren't mutually exclusive.
But people don't like to admit that, because to do so means they have to think about a nasty part of history which they'd rather forget. This is the case in a lot of post-colonial nations. New Zealand for example, has a lot of racist incidents in the past, but people don't like to refer to them. A good example of this is Parihaka. Peaceful resistance to British land seizures resulted in British troops forcibly removing some 1600 Maori from their homes, before destroying the houses and fields. Many of the people were removed to the South Island - a separate tribal region - and remained there several years. If these, and other atrocities against Maori are brought up, the inevitable response is either one I listed above("It happened years ago, get over it!"), or a balancing act is invoked: "Yeah, well Maori used to kill people and eat them!", bringing another atrocity to the argument. Either way, the experience of a group of people is pushed aside, in order for a more friendly, and easier-to-live-with narrative to survive.
Key point: I wouldn't call these people racist. I would think that they're uncomfortable with history, and aren't aware of the benefits that they accrue by being white, or the disadvantages that others receive by not being white. More to the point, they're unable to say, "Yeah, I have some benefits of being white, which made my hard work easier."
I agree with both of the explanations offered already but would like to add a particularly Irish one. Irish historians are familiar with a phenomenon we call MOPE syndrome (Most Oppressed People Ever). This is a tendency to try to place the Irish experience in the context of every historical atrocity. So the Famine becomes a Holocaust, indenture becomes Slavery and Northern Ireland becomes an Apartheid state. This was agrivated by a bad history version of colonial theory which pushed all Irish history into a crude colonial model and denied the existence of any privilege for the Irish as white, Christian Europeans.
I have asked around and apparently the Slavery myth is not heard much in universities (even from very Republican students). It seems to be more of an Internet meme. Unfortunately I have seen it treated as gospel on Irish subs and websites.
‘Irish slaves’: the convenient myth
by Liam Hogan, 14 January 2015
"It was with a heavy heart and no small amount of anger that I decided it was necessary to write a public refutation of the insidious myth that the Irish were once chattel slaves in the British colonies. The subject of this myth is not an issue in academic circles, for there is unanimous agreement, based on overwhelming evidence, that the Irish were never subjected to perpetual, hereditary slavery in the colonies, based on notions of ‘race’. Unfortunately this is not the case in the public domain and the ‘Irish slaves’ myth has been shared so frequently online that it has gone viral."