The term Yankee (also Yank) has a number of possible meanings, but in almost all contexts, it refers to someone of American origin or heritage. Within the USA, its popular meaning has varied over time. Historically, the term usually refers to residents of New England, as used by Mark Twain in A Connecticut Yankee in King Arthur's Court. During and after the American Civil War, its popular meaning expanded to include any Northerner or resident of the Union, and included any resident of the Northeast (New England, Mid-Atlantic, and upper Great Lakes states). Over time, however, the term has since reverted to its 18th century geographic indication of New England, except when the speaker is from the South. Outside the USA, Yank or Yankee is one of the lesser derogatory slang terms for any American, whether from New England or not.

Origins of the word
The term Yankee now means residents of New England, of English ancestry, although that was not the original definition. (See origin of the term above). The Yankees diffused widely across the northern United States, leaving their imprint in New York, the upper Midwest, and places as far away as Seattle, San Francisco and Honolulu.
The fictional character Thurston Howell III of Gilligan's Island, a graduate of Harvard University, typifies the old Yankee elite in a comical way.
In the 21st century the systematic Yankee ways had permeated the entire society through education. Although many observers from the 1880s onward predicted that Yankee politicians would be no match for new generations of ethnic politicians, the presence of Yankees at the top tier of politics in the 21st century was typified by Presidents George H. W. Bush, Democratic National Chairman Howard Dean and Democratic presidential nominee Senator John Forbes Kerry, scion of the old colonial Forbes family.

Yankee cultural history

Contemporary uses
Within the United States, the term Yankee can have many different contextually and geographically-dependent meanings.
Traditionally Yankee was most often used to refer to a New Englander (in which case it may suggest Puritanism and thrifty values), but today refers to anyone coming from a state north of the Mason-Dixon line, with a specific focus still on New England. However, within New England itself, the term refers more specifically to old-stock New Englanders of English descent. The term WASP, in use since the 1960s, refers by definition to all Protestants of English ancestry, including Yankees and Southerners, though its meaning is often extended to refer to any Protestant white American.
The term "Swamp Yankee" is used in rural Rhode Island, eastern Connecticut, and southeastern Massachusetts to refer to Protestant farmers of moderate means and their descendants (as opposed to upper-class Yankees). The most characteristic Yankee food was the pie; Yankee author Harriet Beecher Stowe in her novel Oldtown Folks celebrated the social traditions surrounding the Yankee pie.
In the American South, the term is sometimes used as a derisive term for Northerners, especially those who have migrated to the South. As some Southerners put it, "A Yankee is a Northerner, and a Damnyankee [written and pronounced as one word] is a Northerner who moves (or comes) South". Southerners, by and large, resent being labeled "yankee" when travelling abroad.
A humorous aphorism attributed to E.B. White summarizes these distinctions:

To foreigners, a Yankee is an American.
To Americans, a Yankee is a Northerner.
To Northerners, a Yankee is an Easterner.
To Easterners, a Yankee is a New Englander.
To New Englanders, a Yankee is a Vermonter.
And in Vermont, a Yankee is somebody who eats pie for breakfast.
Another variant of the aphorism replace the last definition with "an outhouse". There are several other folk and humorous etymologies for the term.
One of Mark Twain's most famous novels, A Connecticut Yankee in King Arthur's Court popularized the word as a nickname for residents of Connecticut.
It is also the official team nickname of a Major League Baseball franchise, the New York Yankees.

In the United States
In English-speaking countries outside the United States, especially in Australia, Canada, Ireland, New Zealand and the United Kingdom, Yankee, almost universally shortened to Yank, is used as a derogatory, playful or referential colloquial term for all Americans.
In certain Commonwealth countries, notably the United Kingdom, Canada, Australia and New Zealand, "Yank" has been in common use since at least World War II, when millions of Americans were stationed in the UK and Australia. Depending on the country, "Yankee" may be considered mildly derogatory.
The term has evolved, through the use of Cockney Ryhming Slang, to the word "Septic Tank", or just "Septic". This slang form is heard in Australia, as well.(web|url=http://www.news.com.au/dailytelegraph/story/0,22049,21906321-5001023,00.html?from=public_rss|title=Ndou ready for cocky Seppo|author=Grantlee Kieza|publisher=The Daily Telegraphdate=2007-06-15|quote=The American talks a good game and he can back it up. He doesn't have much punching power but he's shifty and cagey, an awkward, frustrating survivor.}}</ref> (Yankee - Yank - Septic Tank - Septic - Seppo) in Australia.[3]
Recent usage in Europe indicates that Australian tourists have been called "New Yanks."

In other parts of the world

Swamp Yankee
Yankee Doodle
Yankee Doodle Dandy
Jonkheer Further reading

Butsee H. Logemay, "The Etymology of 'Yankee'", Studies in English Philology in Honor of Frederick Klaeber, (1929) pp 403–13.
Fleser, Arthur F. "Coolidge's Delivery: Everybody Liked It." Southern Speech Journal 1966 32(2): 98–104. Issn: 0038-4585
Harold Davis. "On the Origin of Yankee Doodle", American Speech, Vol. 13, No. 2 (Apr., 1938), pp. 93–96 in JSTOR
Kretzschmar, William A. Handbook of the Linguistic Atlas of the Middle and South Atlantic States (1994)
Lemay, J. A. Leo "The American Origins of Yankee Doodle", William and Mary Quarterly 33 (Jan 1976) 435–64
Mathews, Mitford M. A Dictionary of Americanisms on Historical Principles (1951) pp 1896 ff for elaborate detail
Ruth Schell, "Swamp Yankee", American Speech, 1963, Volume 38, No.2 (The American Dialect Society, Published by Duke University Press ), pg. 121–123. accessed through JSTOR
Oscar G. Sonneck. Report on "the Star-Spangled Banner" "Hail Columbia" "America" "Yankee Doodle" (1909) pp 83ff online
Stollznow, Karen. 2006. "Key Words in the Discourse of Discrimination: A Semantic Analysis. PhD Dissertation: University of New England., Chapter 5.