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.

Founded in 1921, the Philadelphia firm of Louis T. Klauder and Associates specializes in the design and evaluation of railroad and rail transit systems, including equipment, infrastructure and operations. Their collection consists of selected job files covering Klauder's work for the Federal Office of High Speed Ground Transportation in developing the first U.S. high-speed rail project in the Boston-Washington Northeast Corridor during the late 1960s and early 1970s. The collection also includes smaller job files on tangential rail projects and a series of files Robert B. Watson, former Northeast Corridor project coordinator for the Pennsylvania and Penn Central Railroads, brought with him when he joined Klauder in 1972.

Professional career files of mechanical engineer Robert B. Watson (1931-) documenting his work on the development of high-speed trains in the years between 1966 and 1998, especially his involvement in the Northeast Corridor Demonstration Project and the development of the first generation "Metroliners."