How to write it？
アメリカ、亜米利加、米国、米
When writing America in Japanese, You can use either katakana or kanji.
We rarely use hiragana except in papers aimed at children.
Advanced Tips
Why 米国?
In Japanese, we sometimes use one or two kanji, which is a combination of a certain kanji + 国.
We usually write foreign countries in katakana, but we also write them in kanji only.
These kanji usually have a similar sound to the original pronunciation.
And we choose one of the kanji, usually choose the first kanji.
Adding 国 makes the contract version for the kanji name of the foreign country.
So for America we can choose 亜, but in reality we use 米.
There may be many reasons, but I will introduce two famous ones.
- Because the strongest accent of America is ‘me’, which is 米 of 亜米利加.
- Because 亜 is familiar to the kanji that represent of Asia.
Other examples
England イギリス 英吉利 英国
Germany（Deutschland） ドイツ 独逸 独国
Australia オーストラリア 濠太剌利 濠州
France フランス 仏蘭西 仏国
Europe ヨーロッパ 欧羅巴 欧州
