Flag Day in Mexico takes place on February 24, 2021. Día de la Bandera ("Flag Day") is a national holiday in Mexico. It was established by the President of Mexico, General Lázaro Cárdenas, before the monument to General Vicente Guerrero, first to pledge allegiance to the Mexican flag on March 12, 1821.
The date was selected because more than a century earlier (February 24, 1821), the "Plan of Iguala" or "Plan of the three guarantees" was proclaimed. This plan was based in three principles: "Religion, Independence and Unity", which were represented on the flag's colors. On this same date, Jose Magdaleno Ocampo tailored the first three color flag for what would soon be an independent Mexico. This flag, commonly known as the "Pendon Trigarante", had the colors: white, green and red in that order, arranged diagonally with three eight-point gold stars, one on the center of each color banner.
When the Pledge is recited, it is customary to salute the flag with the raised arm Bellamy Salute while speaking. When the flag is being paraded, the arm is held across the chest, palm parallel to the ground. (With material from: Wikipedia)