At the Fifth International Conference of American States in Santiago, Chile, governments discussed new ways to improve hemispheric cooperation. In this setting, the idea of a Pan-American highway gained attention as automobiles began to replace rail travel for people and goods.
The First Pan American Congress of Highways opened in Buenos Aires, helping turn the highway idea into a coordinated technical and diplomatic effort. Delegations shared road-building practices and pushed for an inter-American route plan rather than separate national projects.
Representatives from Central American countries, Mexico, and the United States met in Panama and created an Inter-American Highway Commission. The commission’s purpose was to plan a continuous highway from Panama north to the U.S.–Mexico border, moving the project from discussion to formal oversight.
Field reconnaissance began as engineers surveyed feasible routes through difficult terrain, especially in Panama and Honduras. The commission met to review tentative alignments, setting up the technical groundwork needed for later construction across multiple countries.
By the early 1930s, the Inter-American Highway became an organized program with the goal of connecting capital cities by paved road. U.S. participation was channeled through the Bureau of Public Roads as a cooperating agency for surveys, design, and construction assistance.
Countries signed a hemispheric agreement committing to the rapid construction of their highway sections. This convention provided an international legal framework and signaled that the road network was a shared regional priority, not just a set of national projects.
The Pan-American Highway convention entered into force, strengthening expectations that participating countries would follow through on planning and construction. With this step, international coordination became more formal even as funding and construction capacity still varied widely by country.
During World War II, U.S. planners viewed overland access to Panama as a security concern tied to the Panama Canal. The U.S. Army Corps of Engineers began work in 1941 on a key missing segment between Costa Rica and Panama, where no road connection had existed.
Mexico finished and opened its portion of the route, a major milestone because it created a continuous backbone from the U.S. border deep into the network. Mexico’s completion also showed that national investment could move faster than the multi-country segments that depended on shared assistance.
With U.S. assistance in several countries, the remaining Central American portions opened to through traffic, allowing vehicles to travel the Inter-American Highway corridor from Mexico into Panama. This marked a shift from isolated national road segments to a functioning international corridor across Central America.
A major paving project in Panama marked the end of roughly three decades of U.S. participation in Panama highway construction. The work improved safety and travel time on a difficult stretch and signaled that the Central American corridor was shifting into a maintenance-and-upgrading phase.
By 1967, the Inter-American Highway objective of a continuous road corridor from Mexico to Panama City was considered achieved, even though road surface quality varied (gravel, dirt, and asphalt in different places). This completion closed the main 1920s–1960s development arc in Central America and set the stage for later modernization efforts rather than initial route-making.
Even as Central America gained a usable corridor, the Pan-American system still did not become a single uninterrupted road because the Darién Gap between Panama and Colombia lacked a highway. Environmental concerns, Indigenous opposition, and security risks helped keep this section roadless, limiting truly continuous international travel by car beyond Panama.
Pan-American Highway development across Central America (1923–1974)