Adjetivos de nacionalidad y las traducciones (Adjectives of Nationality and Their Translations)

Remember that Spanish adjectives must agree with (match) the noun or pronoun that they modify or describe. This set of terms has only the singular forms of these adjectives. There are also 3 adjectives whose endings can be used for both masculine and feminine. By the way, why do you think Brazilians and U.S. citizens were included in this set of nationalities?