Before diving into the incredibly confusing origins of carnival, I thought it was best to try come up with a definite list of who is actually doing the celebrations. A map is what's needed!
Turns out, the joke was on me as this question is not nearly as easy to answer as you might think. It starts off with the first question we posed in the introduction: What even is carnival? The term in many parts of the world, has come to mean something akin to 'big street party to celebrate cultural heritage'. This is rather broad and unhelpful for our purposes, since it would probably contain every single country in the world. After all, who doesn't like a good party now and then?
But carnival across much of the non-English speaking world has a more specific meaning. By these traditions, carnival (or its alternative names in Europe) is derived from medieval religious traditions, referring only the short period which leads up to Ash Wednesday, or official start of Lent. This makes the dates of carnival vary slightly each year, as the dates of Easter (set by lunisolar calendar) defines the date of Ash Wednesday, hence the dates of carnival.
But even this is too simple as we can get trapped in the details. Does the whole country need to celebrate or just certain communities? What if there's no celebrate at all but there's cultural practices tied to Ash Wednesday? Does it matter if celebrations used to follow the Easter calendar but now don't? and who's Lent are we talking about, anyway? The orthodox church has a different Easter, thus a different Ash Wednesday and, yes, a different carnival!
Researching carnival traditions from around the world, there seems to be four or five major categories of countries we could consider:
Countries that celebrate carnival in big, public events according to the Catholic tradition, e.g. Germany or Brazil.
Countries that celebrate carnival in big, public events according to the Orthodox Christianity tradition, e.g. Greece or Ukraine.
Countries who have imported big public celebrations, directly inspired by carnival traditions from other places, or had carnival traditions in the past that have since been decoupled from Easter e.g. Namibia, Canada.
Countries that acknowledge the importance of Easter in some way (i.e. are Christian) but only engage in minor cultural practices to celebrate, e.g. Pancake Tuesday in the United Kingdom, Tłusty Czwartek in Poland.
Countries that have large annual celebrations which completely unrelated to Easter, but have come to be known as 'carnivals' for branding reasons, e.g. Batik in Indonesia.
For my map I'm only gonna consider the first three cases: those carnivals that come from the pre-Lent tradition and its spin-offs and copycats. I'm doing this because these celebrations are both in the lineage of carnival's origins while also maintaining the big, splashy, colorful street parties and parades that come to mind when one thinks of carnival.
And there we have it! The colorful countries of carnival!
There are some notable absences from Catholic nations, such as Ireland or the Philippines and the notable inclusion of non-Christian nations who have nonetheless decided to make the celebration their own, like Japan. Then there are the oddballs of Denmark and the UK, who both re-imported carnival from overseas traditions, despite both celebrating Easter and having deep, cultural ties to their carnival-mad neighbours in Europe.
Remember, its not everyone's tradition in the highlighted nations to celebrate (I don't mean people that don't like to party!) and, conversely, there are probably groups in the grey nations that do celebrate carnival traditions.
What do you think? Does your country do a big carnival celebration, but has been missed out by me? Let me know!