The Spanish language is classified as a Romance Language. Other romance languages include Italian, french, portuguese, and others. These romance languages developed from the "vulgar" (spoken) form of Latin that was used in the roman empire. Latin is considered an italic language from the indo-european family. the indo-european family is the name given to the family of languages that moved throughout europe and asia as a result of colonialism.
In central and south america, there exist many indigenous languages  known as "middle american).  These include many different dialects including indigenous indian languages, too.  
 South america is known as one of the most linguistically diverse areas of the world.  the Three major language groups include the chibchan, the Ge-pano-caribe, and the macro-ge. 
Percentages of Non english background speakers in US states (according to the 1990 census):
Ca:        31.5%
Az:        20.8%
Tx:        25.4%
Fl:        17.3%
NY:        23.3%
RI:          17%
ND:        7.9%
SD:        6.5%
Ia:        3.9%
Mn:        5.6%
Ne:        4.8%
The top 3 most natively spoken languages in the world (according to Wikipedia):
1.  chinese mandarin
2.  spanish
3.  english