The year 2006 marked the 50th Anniversary of the Eisenhower Interstate Highway System (hereafter referred to as the System). During the design and construction of the System, geotechnical engineers faced many challenges to construct a highway system that would facilitate the movement of traffic, specifically military traffic. The Cold War was at its height 50 years ago. Reliable transportation was needed from the east–west and the north–south borders of the United States as quickly and efficiently as possible. This required the design and construction of a highway system through many different geologic formations, several different climates, and many different soil depositions. Karl Terzaghi’s 1925 Erdbau Mechanic was barely 30 years old. Many of the challenges first had to be recognized and defined before they could be understood and solved. To accomplish the task, many new and innovative geotechnical engineering technologies were developed, along with enhancements to the traditional designs. The product of these efforts was an enviable transportation system that met military requirements and became a pillar to support previously unparalleled economic growth of the country. Maintaining and upgrading this system to meet continuing and new needs left more than one challenge for the future.