This is also a problem that exists within countries. My RSS feed is littered with Canadian independent (national) news agencies not defining what municipality article headlines relate to. E.g. "Mayor pushes back against province on xyz issue". Okay, that might be huge news for Timmins Ontario , but maybe BAU for Toronto. Even skimming the lead paragraph doesn't define the city often.

*Editting with a point: Perhaps everyone assumes a local audience.

Americans, hm? I see what you did there.

Good luck. Americans won't even differentiate Washington State and Washington D.C. Even the AP guidelines say that "Washington" is ubiquitous shorthand for "Washington D.C." and recommends against shortening it to "D.C."