Final answer:
Since 1938, the nationalization of the oil industry by President Lázaro Cárdenas has been a symbol of Mexican independence, with the founding of PEMEX marking a sovereign control over oil resources, supported tacitly by the Roosevelt administration.
Step-by-step explanation:
Since 1938, the nationalization of the oil industry has served as a symbol of Mexican independence from foreign domination. This move was under the leadership of Mexican President Lázaro Cárdenas, who, invoking the Mexican Constitution of 1917, nationalized all oil production in Mexico, including the assets of foreign companies. President Franklin D. Roosevelt's administration, focusing on domestic issues with the New Deal and advocating a Good Neighbor Policy towards Latin America, did not oppose Mexico's actions. As part of this move, the state-owned company Petróleos Mexicanos, known as PEMEX, was established. Despite objections from foreign companies, Mexico gained full control over its oil resources, which became an enduring point of national pride and a symbol of sovereignty, particularly with the advent of World War II when PEMEX prospered as the Allied nations prioritized anti-fascist solidarity.