He Flag of Mexico is rich with historical symbolism. The tricolors of white, green and red with the coat-of-arms centered in the white middle stripe were adopted by Mexico following their independence from Spain during the War of Independence in 1821.
There have been adjustments to the flag throughout background but the coat of arms has ever featured a royal eagle holding a serpent on top of a cactus. The current coat of arms was designed in 1968 by Helguera. Legend says that the Aztecs, then a nomadic tribe wandering throughout Mexico, were waiting for a sign from the gods telling them to build their capital city. Their god, Huitzilopochtli told them to search until they found a place where they saw an eagle, devouring a serpent while perched on a prickly pear tree, growing out of a rock submerged in a lake. After drifting for two hundred years, they found this mythical eagle on a small island in Lake Texcoco and built their capital, Tenochtitlan, where the main plaza in Mexico City is now located.
Through the years the three colors of green, white and red on the flag have remained the same but the meaning of these colors has changed. The green stripe represents Independence from Spain or may signify Hope. The white stripe represents purity of the Catholic religion or Unity. The red stripe represents Heroes blood or Religion.
When the flag of Mexico is paraded in front of a crowd, bystanders raise their right arm, put their hand on their chest parallel to the heart. The hand is level with the palm facing the floor. This salute is referred to as the El Saludo Civil de la Bandera Nacional. On February 24 annually a national party, Dia de la Bandera, Flag Day is held. This commemorates this day in 1821, when all of the factions fighting in the Mexican War of Independence combined together to form the Army of Three Guarantees.