Sure, if you're picking and choosing. United States of America is the formal name, while the other 2 are informal. Canada is Dominion of Canada and Mexico is United Mexican States. So it should be either CAM or DUU if you're being consistent.
If you're being pedantic, at least be correct. Canada hasn't formally or informally been called the Dominion of Canada in any internal context since 1951.
1867 British North America Act (aka Constitution Act): "one Dominion under the name of Canada". It was a last minute change from "Kingdom" to "Dominion" to avoid a hypothetical diplomatic incident with the US. It was never the official name, only a title. Official documents were allowed to use either, for a period, but it was never the formal name.
The last vestiges were the renaming of "Dominion Day" to "Canada Day" in 1982. Any use of the name "Dominion of Canada" is now either archaic, ironic, or a hypercorrection.
Well actually its ABBBCCCDDEGGHHJMNPSSSSTU if you only count countries(greenland is part of denmark technically) but there are a shitton of territorial disputes in that area so im not gonna argue with anyone in comments...