TheatreHistory.com
Theatre History: American Musical Theatre: An Introduction
A commercial website that provides a solid history of American musical theatre. Includes summaries of many musicals through history. Focus is on shows before 1960.
Yale University
Yale New Haven Teachers Institute: Musical Theater
Introductory site focusing on American musical theatre and Broadway. Shows how these parts can be taught in the classroom. Useful for teachers and students working with music theater.
Musicals 101
Musicals101: History of the Stage Musical 1910 1920
From Jerome Kern's Americanized shows to the Ziegfeld Follies, the stages saw a whole new type of musical from 1910-1920.