> Wikipedia is a better source for common usage than the US state department, and they've explicitly resisted changing the spelling.

Why would common usage matter for something that recently changed? Of course the former name is more commonly used. The State Department is the better source since they’re the ones dictating how the US government as a whole interacts with Türkiye.

It doesn’t matter what the people in the US call countries if we’re not the ones making deals and talking to their leaders. I can convince everyone that Russia would be call Assuria but that doesn’t make it’s name. The only ones that have authority of the name of a country is the country itself.