Kodak popularized photography and made it available to the general public. Today, Kodak film is made in the factory in Rochester, New York. Each film starts as a giant roll which is put in a light-tight box called “a casket.” Then it gets transported to the finishing plant where it goes through three main steps.
The first step in manufacturing film is creating it into a base, which is heated, stretched, and formed into a large rolled sheet up to 12,000 feet (3,657.6m) long. Step two is getting the film roll sensitized. Emulsions and chemicals are applied to sensitize the film base and prepare it for film finishing. The third and final step is cutting the film, perforating it, labeling it, and preparing it for shipping.
Source: https://www.diyphotography.net/this-video-takes-you-behind-the-scenes-of-making-kodak-film/