The national flag of Uruguay is one of the three official flags of Uruguay along with the flag of Artigas and the flag of the Treinta y Tres. It has a field of nine equal horizontal stripes alternating white and blue. The canton is white, charged with the Sun of May, from which 16 rays extend, alternating between triangular and wavy. The flag was first adopted by law on 18 December 1828, and had 19 alternating stripes of white and blue until 11 July 1830, when a new law reduced the number of alternating stripes to nine. The flag was designed by Joaquín Suárez.

The national flag of the Argentine Republic, often referred to as the Argentine flag, is a triband, composed of three equally wide horizontal bands coloured light blue and white. There are multiple interpretations on the reasons for those colors. The flag was created by Manuel Belgrano, in line with the creation of the Cockade of Argentina, and was first raised at the city of Rosario on February 27, 1812, during the Argentine War of Independence. The National Flag Memorial was later built on the site. The First Triumvirate did not approve the use of the flag, but the Asamblea del Año XIII allowed the use of the flag as a war flag. It was the Congress of Tucumán which finally designated it as the national flag, in 1816. A yellow Sun of May was added to the center in 1818.