How many countries have disappeared since 1900?

How to get close to this number

Scale from the survivors. There are around two hundred countries today, and the twentieth century saw empires dissolve, colonies become states, federations split and states merge. A century of that churn plausibly produces disappearances on the same order as the current count — which is the reasoning that gets you to the right magnitude.

The two examples in the explanation carry most of the weight: one union became fifteen countries and one federation became seven. Dissolutions are not one-for-one replacements; a single state vanishing can create many, which means the count of disappeared states grows faster than intuition suggests during any period of fragmentation.

This is the softest figure on this page and the honest thing is to say so. What counts as a sovereign state that ceased to exist depends on recognition, on whether a renamed state counts as a new one, and on how you treat entities that existed briefly or were recognised by almost nobody. The figure is a defensible order of magnitude built from historical registers, not a definitive list.