Why in spanish US is EEUU?

"Estados Unidos" is abbreviated as "EEUU" (also: EE. UU.) because in

Spanish the abbreviation for a plural item doubles the letter of the

abbreviation. The same is done, for example, with the abbreviation for

"Fuerzas Armadas" (= Armed Forces), which is "FF. AA.", indicating

that the abbreviation relates to a plural term.

The English language knows this custom too, albeit in a few cases

only. For instance, the abbreviation for "page" in singular is "p.",

while "pages" in plural are abbreviated as "pp.".

Sometimes, however, the abbreviation "EUA" (Estados Unidos de America)

for the United States is indeed used in Spanish, but not often.