From the Library of Congress:
This classic work, a mix of live action and animation, was adapted from Winsor McCay’s famed 1905 comic strip "Little Nemo in Slumberland." Its fluidity, graphics and story-telling was light years beyond other films made during that time. A seminal figure in both animation and comic art, McCay profoundly influenced many generations of future animators, including Walt Disney.
See the other 24 films tapped for preservation here.
And now, without any further adieu: