His appointment to the Secretariat of Foreign Affairs by President Manuel Ávila Camacho marked an end to the Post-Revolutionary domination of politicians from the North of the country. With his co-cabinet member Miguel Alemán Valdés (Secretary of the Interior), he "gave Mexico the most progressive foreign policy and the most orderly internal government in the nation's history." By 1941, he had successfully settled all foreign claims against the government stemming from the Cárdenas-era expropriations. He negotiated a favorable economic treaty, fixed the peso to the United States dollar, and secured loans for industrial development from the Export-Import Bank of the United States.