Issued by Mexico in 1958, this airmail stamp commemorates the 20th Anniversary of the National Petroleum Expropriation (1938–1958), a defining moment in Mexico’s economic sovereignty. The design features oil industry infrastructure symbolizing the nationalization that led to the creation of PEMEX. Printed in a strong industrial green tone, the stamp reflects mid-century modernization and energy independence themes. The inscription “Petróleos Mexicanos al Servicio de la Patria” highlights petroleum’s role in national development. A significant thematic item for collectors of industry, energy, and Latin American historical issues.