As seen on the main page, American Winsor McCay was one of the first animating artists. Most animation developed in the United States also, as can be seen with such places as the Walt Disney Company and Warner Brothers Studios. For the last couple of decades in America, animation has been mostly for television but there were those people that were trying to break out of that mode.

Image from The Illusion of Life: Disney Animation, and proves that "attitudes can be achieved in the simplest of shapes," as can be seen with the half-filled flour sack.

Disney Animation
Walt Disney Productions is no doubt the company that had the most impact on the animation industry. It introduced the first full feature-length, Snow White, which introduced objects moving at different speeds to show distance and a sense of realism. Walt Disney Animation managed to be the first to actually analyze the world for what it is and animate it, such as how you know how animals feel based upon their actions, not because they can talk to you, because, well, they can't. While this can be remedied with personification, actions speak louder than words, and sometimes one would try to add in realism by making animals act the way they usually do. They analyzed how Timing is extremely important along with the Squash and Stretch effect. One example is the bouncing ball, where it was discovered that a ball would have more weight if the illustrations were closer together at the top and farther apart as the ball would hit the bottom. In fact, Disney Animation tried to use every trick in the book to make a character lively. Walt Disney wanted realism, and a lot of it too. There were also times that those realistic images didn't look lively enough, as they need to be exaggerated. people questioned Walt's judgment, because he wanted realism. The workers then realized that when Walt meant realism, he meant he wanted the audience to be able to relate to the character, make the expressions look like the audience would immediately know how the character was feeling, instead of plain expressions that humans were already capable of making. There are also those who would argue that Disney insulted the literary texts that were "Disneyficated", as critics argued that it betrayed the spirit of the original. As true as the statement is, still the Disney formula worked with the mass audience and gained huge amounts of popularity among the public.

Bugs Bunny, Elemer Fudd, Daffy Duck, Wile E. Coyote, and Road Runner in an image illustrated by Chuck Jones.

Warner Brothers Animation
Leon Schlesinger produced the Merrie Melodies, Looney Tunes, Porky and Beans, Daffy Duck and Bugs Bunny series, with artistic talents of Chuck Jones, Tex Avery, Bob Clampett, and Abe Levitov. Chuck Jones especially was one of the few Hollywood animators who is flexible enough to keep up with changing styles and techniques. He also learned about timing and action from Charlie Chaplin, who's studio was conveniently next door. Warner Brothers just basically decided to take part in the animation industry, basically. They didn't really introduce anything new to animation.

Other Animated Cartoons
Around the 1930s, animation had become a real profession. This was also known as The Golden Age of American Cartoons. Cartoons such as Tom and Jerry, Betty Boop, Felix the Cat, and countless others flourished during this time period. The 1940s and '50s saw reactions against the Disney style. Artists such as Bill Hanna and Joe Barbera, Tex Avery, Paul Terry, Walter Lantz, and Chuck Jones continued to make animated features but with a more comedic touch to it. Usually, the quality is lesser than those of a full length animated movie.