What was the first film that used cel animation?

While there are earlier examples of animation using cel techniques, the first commercially released film widely considered to be "cel animation" is Snow White and the Seven Dwarfs (1937).

This is due to several key factors:

* It was the first full-length animated feature film. This helped popularize cel animation as a viable technique for feature films.

* Disney perfected the cel process. They developed techniques for layering cels, creating smooth motion, and achieving vibrant colors, establishing standards still used today.

* It was a critical and commercial success. Snow White's popularity solidified cel animation as a dominant force in animation for decades.

While there were other early examples of cel animation, Snow White's impact on the industry and its lasting legacy solidify its position as the first widely recognized and influential use of cel animation.