Supercontinent

A supercontinent is a large area of land which has more than one continental core, or craton. They are formed by continental plates coming together. Continental plates have periodically collided and assembled in periods of orogeny (mountain-building) to form supercontinents. The cycle of supercontinents forming, breaking up, separating, and re-forming through plate tectonics happens about every  2000 million years.

Eurasia is certainly a supercontinent, but the Americas are usually thought of as separate continents. Even more clearly, Gondwana and Laurasia were supercontinents formed by the breakup of the global supercontinent Pangaea.

The land bridge between North and South America is geologically a rather temporary connection.  Because of this, the Americas are usually not described as one supercontinent.

 Ancient supercontinents 
Throughout Earth's history, there have been many supercontinents.  In order of age (oldest to newest), the ancient supercontinents were:
Supercontinent nameAge (Ma)Period/Era RangeCommentVaalbara3,636–2,803Eoarchean-MesoarcheanAlso known as a supercraton or just a continentUr2,803–2,408Mesoarchean-SiderianKnown as both a continent and a supercontinentKenorland2,720–2,114Neoarchean-RhyacianThe continents may have also formed into two groupings Superia and SclaviaArctica2,114–1,995Rhyacian-OrosirianNot generally known as a supercontinent, depending on definitionAtlantica1,991–1,124Orosirian-StenianNot generally known as a supercontinent, depending on definitionColumbia (Nuna)1,820–1,350Orosirian-EctasianRodinia1,130–750Stenian-TonianPannotia633–573EdiacaranGondwana550–175Ediacaran-JurassicFrom the Carboniferous, formed part of Pangaea, not always known as a supercontinentPangaea336–175Carboniferous-Jurassic

 References 

Continents