Transactions of the American Society of Civil Engineers, Vol. LXVIII, September 1910: The New York Tunnel Extension of the Pennsylvania Railroad is a comprehensive and authoritative record detailing one of the most ambitious and transformative engineering projects of the early twentieth century. This volume meticulously documents the conception, design, and construction of the Pennsylvania Railroad’s monumental tunnel extension into New York City, a feat that revolutionized rail transportation and urban connectivity. The book opens with an in-depth exploration of the challenges faced by engineers and planners as they sought to overcome the formidable obstacles presented by the Hudson River and the densely built urban landscape of Manhattan. It provides a thorough analysis of the technical, logistical, and financial considerations that shaped the project, including the selection of tunnel routes, the development of innovative construction techniques, and the management of complex urban infrastructure. Richly illustrated with detailed diagrams, maps, and photographs, the volume offers readers a rare glimpse into the methods and machinery employed during the construction process. It covers the use of shield-driven tunneling, the handling of difficult geological conditions, and the implementation of advanced ventilation and safety systems. The narrative also highlights the collaboration between engineers, architects, and city officials, emphasizing the importance of interdisciplinary cooperation in achieving such a monumental undertaking. In addition to technical details, the book delves into the broader social and economic impacts of the tunnel extension, examining how it facilitated the growth of New York City as a commercial and transportation hub. It discusses the transformation of Penn Station into a grand gateway for millions of passengers and the lasting legacy of the project in shaping modern urban transit systems. With contributions from leading engineers of the era, including firsthand accounts and critical analyses, this volume stands as an essential resource for historians, engineers, and anyone interested in the history of civil engineering and urban development. It captures the spirit of innovation and determination that defined the era and continues to inspire large-scale infrastructure projects to this day.