Spanish As Official Language

Nations in which Spanish is an official language (de facto or de jure). 

All countries have majority Spanish-speakers except Belize, Western Sahara and United States.

It is an unofficial language in Belize, due to historical reasons and it being a majority language. 

In the US spanish is only official with english in Puerto Rico and New Mexico. 

In Gibraltar though not an official language it is spoken by a majority of the people.