America and the Creation of Santa Claus: A Guide
The American Santa Claus is generally considered to have been the invention of Washington Irving and other early nineteenth-century New Yorkers, who wished to create a benign figure that might help calm down riotous Christmas celebrations and refocus them on the family. This new Santa Claus seems to have been largely inspired by the Dutch tradition of a gift-giving Sinterklaas, but it always was divergent from this tradition and was increasingly so over the course of the nineteenth and twentieth centuries. So, the American Santa is a largely secular visitor who arrives at Christmas, not the 6 December; who dresses in furs rather than a version of bishop's robes; who is rotund rather than thin; and who has a team of flying reindeer rather than a flying horse. At first his image was somewhat variable, but Thomas Nast's illustrations for Harper's Illustrated Weekly (1863-6) helped establish a figure who looks fairly close to the modern Santa. This figure was taken up by various advertisers, including Coca-Cola, with the result that he is now the 'standard' version of the Christmas visitor and has largely replaced the traditional Father Christmas in England.
The Origin of American Christmas Myth and Custom - By B.K. Swartz, Jr., Emeritus Professor at Ball State University (this page is now hosted on arthuriana.co.uk by kind permission of B. K. Swartz, Jr.). A very nicely illustrated schematic version of the evolution of Santa Claus from St Nicholas, with extremely good coverage of the development of Santa Claus (including dates for the first appearance of various features).
Christmas Reborn: The Creation of a Consumer Christmas - An interview with Professor Stephen Nissenbaum, author of an important book on the nineteenth-century American 're-invention' of Christmas and the creation of Santa Claus, The Battle for Christmas. This interview includes discussion of both of these topics.
Santa Claus Does More Than Deliver Toys: Advertising's Commercialization of the Collective Memory of Americans - An interesting journal article from 2000 that has been made freely available (pp. 207-40 of the PDF). This provides a good summary of the early development of St Nicholas before going into considerable detail on the American tradition of Santa and its evolution and spread.
Santa Claus: Building a Better Father Christmas - A good article which is largely based on Nissenbaum's work, making the case for the American tradition of Santa Claus being the creation of an early nineteenth-century New York elite, who transplanted the Dutch Sinterklaas into New York in a successful attempt to civilise Christmas.
A good short article is Saint Nicholas and the Origins of Santa Claus, from stnicholascentre.org; this includes a good selection of pictures of the American Santa.
Knickerbocker's History of New York - The satirical history by Washington Irving which began the process of creating an American tradition of Santa Claus, as described in the above articles. Another key text in this creation was the poem 'Twas the Night Before Christmas, usually attributed to Clement Clarke Moore. Also important in the process were Thomas Nast's illustrations of Santa Claus from the mid-late nineteenth century, many of which can be viewed online, for example here, here, here, and here.
Did Coca-Cola Invent Santa Claus? - A detailed discussion of the common belief that the modern image of Santa Claus was the sole creation of 1930s Coca-Cola advertising, which rightly rejects this as a myth. Another good demolition of this myth and brief discussion of the nineteenth-century 'creation' of the American Santa Claus is available here: Did the Popular Image of Santa Claus Originate in a Coca-Cola Ad?
Santa Claus and White Rock from 1915 - A well-illustrated site that features a pre-Coca-Cola but still very modern looking Santa Claus advertising 'White Rock' water; these images obviously help support the points made in the preceding articles, though they can now only be accessed via the Internet Archive. See also this article: Coca-Cola's Santa Claus: Not the Real Thing! The following article is Coca-Cola's own take on the myth and the controversy that surrounds it: Coca-Cola and Santa Claus