Which country's flag was designated national by the Congress of Tucumán in 1816? Argentina’s flag was designated as the national flag by the Congress of Tucumán in 1816.
The Congress met in San Miguel de Tucumán during the struggle for independence from Spain. On 9 July 1816 it declared independence for the United Provinces of South America, and on 20 July it formally recognized the light-blue-and-white flag associated with Manuel Belgrano as the national symbol.
Belgrano had first raised a related flag at Rosario on 27 February 1812. The First Triumvirate initially disapproved of its use, but the flag gained official standing as the independence movement developed. The Congress’s 1816 decision transformed it from a revolutionary military banner into the national flag of the newly independent polity.
The familiar Sun of May was added later, in 1818. Thus, 1812 marks the flag’s first raising, while 1816 marks its designation as the national flag—an important distinction behind this question.