Anyway, It is no[STRIKE]o[/STRIKE]t a single country.
So you say the U.S, the Netherlands, etc., but Iran, Iraq, etc(no the)
The United States
is a single, federal, country. Its official name tells us that it is made up of a union of 50 states. Canada is also a a federal union, but it happens to have a name that does not refer to this. The Netherlands is without doubt a single country; its name means 'the low-(lying) countries'.
As bennevis suggested, we use 'the' when the name of the country uses words that are a description of the structure of the country. Many countries have a less formal name that does not require the definite article.
The United States of America, but: [STRIKE]the[/STRIKE]
America.
The United Kingdom, but: [STRIKE]the[/STRIKE]
Great Britain, [STRIKE]the[/STRIKE]
England, t[STRIKE]he[/STRIKE]
Scotland, etc.
The Federal Republic of Germany, but: [STRIKE]the[/STRIKE]
Germany.
The People's Republic of China, but: t[STRIKE]he[/STRIKE]
China