America/Americas

In many parts of the world, America in the singular is commonly used as a name for the United States of America; however, (the) Americas (plural with s and generally with the definite article) is not and is invariably used to refer to the lands and regions of the Western hemisphere. Usage of America to also refer to this collectivity remains fairly common.

While many in the United States of America generally refer to the country as America and themselves as Americans, many people elsewhere in the Americas resent what they perceive as appropriation of the term in this context and, thus, this usage is frequently avoided. In Canada, their southern neighbor is seldom referred to as "America" with "the United States", "the U.S.", or (informally) "the States" used instead. English dictionaries and compendiums differ regarding usage and rendition.

http://en.wikipedia.org/wiki/Americas