The transcontinental railroad was the greatest engineering epic in a century full of them.

The Civil War let the nation turn to another great struggle. While the Central Pacific fought through the high passes of the Sierra, the Union Pacific drove westward across the plains.

The job was done in 1869. Stephen E. Ambrose places its significance alongside that of the Civil War itself—a project that remade a wounded nation both symbolically and materially. The West ceased to be remote; travelers could go from New York to California in a week instead of months.

The UP was by far the largest corporation of its day and thus set the pace for even bigger ones to follow. Moreover, the pervasive federal presence in the project foreshadowed an involvement of government and industry that continues to this day.

—T.A.H.