Well, American Dialects Have Been Studied For

I Am Now Completing Research Supported By Nsf And Neh That Is Mapping Changes In The English Language Through All Of North America, For Both Mainstream And Minority Communities.

But Unlike European Countries, America Has Never Finished A Map Of The United States, Only The Eastern United States Is Covered And A Few Spots Here And There.

Well, American Dialects Have Been Studied For A Hundred Years Or So.

It Appears That The Present-day Form Of African American English Is Not The Inheritance Of The Period Of Slavery, But The Creation Of The Second Half Of The 20th Century.

This African American Vernacular English Shares Most Of Its Grammar And Vocabulary With Other Dialects Of English. But It Is Distinct In Many Ways, And It Is More Different From Standard English Than Any Other Dialect Spoken In Continental North America.