American English, sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. English is the most widely spoken language in the United States and in most circumstances is the de facto common language used in government, education and commerce. Since the 20th century, American English has become the most influential form of English worldwide. American English varieties include many patterns of pronunciation, vocabulary, grammar and particularly spelling that are unified nationwide but distinct from other English dialects around the world. Any American or Canadian accent perceived as lacking noticeably local, ethnic or cultural markers is popularly called "General" or "Standard" American, a fairly uniform accent continuum native to certain regions of the U.S. and associated nationally with broadcast mass media and highly educated speech. However, historical and present linguistic evidence does not support the notion of there being one single "mainstream" American accent. The sound of American English continues to evolve, with some local accents disappearing, but several larger regional accents having emerged in the 20th century. History The use of English in the United States is a result of British colonization of the Americas. The first wave of English-speaking settlers arrived in North America during the early 17th century, followed by further migrations in the 18th and 19th centuries. During the 17th and 18th centuries, dialects from many different regions of England and the British Isles existed in every American colony, allowing a process of extensive dialect mixture and leveling in which English varieties across the colonies became more homogeneous compared with the varieties in Britain. English thus predominated in the colonies even by the end of the 17th century's first immigration of non-English speakers from Western Europe and Africa. Additionally, firsthand descriptions of a fairly uniform American English (particularly in contrast to the diverse regional dialects of British English) became common after the mid-18th century, while at the same time speakers' identification with this new variety increased. Since the 18th century, American English has developed into some new varieties, including regional dialects that retain minor influences from waves of immigrant and enslaved speakers of diverse languages. Some racial and regional variation in American English reflects these groups' geographic settlement, their de jure or de facto segregation, and patterns in their resettlement. This can be seen, for example, in the influence of the Scotch-Irish immigration in Appalachia