The objective of this article is to discuss the actors involved, and the arguments used, in the process leading to the implementation of The Road Plan for Sweden. The Road Plan, a 20-year program to improve and modernize Sweden, aimed to rebuild and adapt the country's network of roads to suit the needs of mass motorization. It marked a breakthrough as a new kind of far-reaching societal planning, with the car as the point of departure. This article analyzes the means by which technical ideas and planning approaches developed elsewhere found their way into the plan. The Swedish road system was connected to the European road network, but the technical ideas of traffic engineeringon which the plan rested derived from an even wider base that reached all the way to the United States. This article investigates and explains the influence of the international road and car lobby—specifically the International Road Federation and its "local branch" the Swedish Road Federation—in encouraging the adoption of American-based traffic engineering ideals in the Swedish Road Plan.