A note on usage: The duration of an individual episode varies from series to series. While some series may be produced as complete half-hour programs, many cartoons are produced as short subjects of 15 minutes or less. These cartoons are grouped and mixed together according to network programming demands. Thus a particular animated series may appear in a number of formats, often anonymously, e.g. The Cartoon Hour.
Generally, animated programs in the United States are comedies, although action/adventure has, from the 1960s on, has been a popular subgenre; from the 1940s to the 1980s, these programs were generally aimed at children. In the 1990s, the rise of The Simpsons led the way for a new genre of animated comedies, generally aimed at adults.