In the US these are done state by state with little consistency. The rivers and streams here in KS are all muddy and graded accordingly. But when they cross into MO they are suddenly pristine.
They're US states, I'm sure if you really wanted to know which specific ones they are, you can look them up, and if you don't want to, OP's point doesn't actually rely on you knowing that they're Kansas and Missouri.
Let's make this about 'murica. Hello, fellow 'murican. Did you already coup a government on this fine day to replace their President with some dictator that will gladly sell out his country to our interests in favour of power? I love the smell of terrorism in the morning. Makes my petro dollar extra bloody.
ok. Seems fairly common across the world. In germany it's common-place as well to use acronyms, sometimes even in speech (mostly for those with longer names like BW for Baden-Württemberg)