• American Spelling
• English Language
• "For Freedom of Spelling: The Discovery of an Art," by H.G. Wells
• Misspelling

• Orthography
• Writers on English Spelling

Examples and Observations:

• British Spelling vs. American Spelling
  "The lexicographerNoah Webster is responsible for many of the differences that distinguish American spelling from British spelling. His American Dictionary of the English Language, which came out in 1828, became the standard for US spelling. He originally wanted Americans to use much more strictly phonetic spelling, but he later compromised with only minor modifications. British spelling has also undergone reform since 1828. Most notably, terror and horror have lost their -our endings. The -isesuffix is relatively new to British spelling."
  (Christopher Davies, Divided by a Common Language: A Guide to British and American English. Houghton Mifflin, 2007)
• British -our and -re Endings
  "Noah Webster, through the influence of his spelling book and dictionaries, was responsible for Americans settling upon -or spellings for a group of words spelled in his day with either -or or -our: armo(u)r, behavio(u)r, colo(u)r, favo(u)r, flavo(u)r, harbo(u)r, labo(u)r, neighbo(u)r, and the like. All such words were current in earlier British English without the u, though most Britons today are probably unaware of that fact; Webster was making no radical change in English spelling habits. Furthermore, the English had themselves struck the u from a great many words earlier spelled -our, alternating with -or: author, doctor, emperor, error, governor, horror, mirror, and senator, among others.
  
  "Webster is also responsible for the American practice of using -er instead of the -re that the British came to favor in a number of words--for instance, calibre, centre, litre, manoeuvre, metre (of poetry or of the unit of length in the metric system), sepulchre, and theatre. . . . Except for litre, which did not come into English until the nineteenth century, all these words occurred in earlier British English with -er."
  (John Algeo and Thomas Pyles, The Origins and Development of the English Language, 6th ed. Wadsworth, 2010)

• The c-s Difference
  "The British [c] spelling of the nouns defence, licence, offence, pretence, and practice has an [s] counterpart in American spelling: defense, license, etc. The British distinction between the noun spelling (licence, practice) and verb spelling (license, practise) is lost. Rather confusingly, the form practice can also be found as an American spelling of both noun and verb. The British use of the [c]-[s] difference to mark nouns and verbs is also found to some small extent in advice-advise, device-devise, prophecy-prophesy."
  (Edward Carney, A Survey of English Spelling. Routledge, 1994)
• Spelling-Reform Efforts in England
  "In Great Britain, interest in spelling reform died down after the sixteenth century but revived during the mid-nineteenth century, especially as a means to make learning to read easier and to help foreigners master English. . . .
  
  "[S]pelling reform received the support of various organizations. For instance, in 1876, the National Union of Elementary Teachers urged the formation of a commission to study spelling reform. In 1871, A.J. Ellis produced still another revised alphabet (called Glossic) for the British Philological Society. The British Spelling Reform Association was organized in 1879 and proposed several modifications of the traditional system. Despite the efforts of these groups, however, the public as a whole never supported extensive spelling reform, and once again reform efforts died down . . .."
  (C. M. Millward and Mary Hayes, A Biography of the English Language, 3rd ed. Wadsworth, 2012)