Louis T. Klauder and Associates (LTK) is a professional rail transportation engineering consulting firm. LTK were hired to work as consulting engineers for a joint project of the United States Department of Transportation and Pennsylvania Railroad called the Northeast Corridor Demonstration Project. This collection contains aerial photographs of the Northeast Corridor railroad route from New York to Boston taken between 1951 and 1965. These images were used to aid in the project. These aerial photographs make up a bulk of the collection. There are several sets of images that show train station exteriors along several routes on the Northeast Corridor. Thirty-eight photographs show the projects test track at Pueblo Army Depot in Colorado. There are four press photographs for Inflight Motion Pictures Inc. and a few renderings of proposed trains.