Links

Light and easy

Verve Music has brief descriptions of many varieties of jazz.
http://www.vervemusicgroup.com/history.aspx?hid=27

Another site with a quick overview of the history of jazz by period.
http://www.soyouwanna.com/site/syws/jazz/jazz.html

Art Kane’s famous group photo with full explanations of those present.
http://www.harlem.org/

Mark Siegel’s website has a concise history of jazz.
http://www.marcsiegelmusic.com/id78.htm

More depth

The early years of jazz that highlights the players.
http://www.redhotjazz.com/

The Chicago Jazz Archive focuses on jazz in that city.
http://www.lib.uchicago.edu/e/su/cja/

Some details about jazz in Kansas City.
http://www.umsl.edu/services/library/blackstudies/basie.htm

Has a year-by-year and decade-by-decade breakdown starting before 1895.
http://www.allaboutjazz.com/timeline.htm

The Thelonious Monk Institute of Jazz has lesson plans for grades 5,8, & 11.  Includes lots of easy to find facts in a bunch of categories:  timeline, important firsts, musicians, glossary, style sheets, education, & more.
http://www.jazzinamerica.org/home.aspv

Along with a bit of history, this site is especially for those learning to play jazz.
http://www.apassion4jazz.net/

Most scholarly

The Institute of Jazz Studies.
http://www.libraries.rutgers.edu/rul/libs/jazz/jazz.shtml

New Orleans jazz.
http://www.tulane.edu/~lmiller/JazzHome.html

The pre-history of jazz, chapter 1 from a book.
http://www.washingtonpost.com/wp-srv/style/longterm/books/chap1/historyofjazz.htm