The red stripe is the right stripe of the Mexican flag when the flag is viewed from the front. In modern civic explanations, red is commonly associated with the blood of national heroes, especially those who fought for independence and defended Mexico.

In older independence-era symbolism, red was associated with union, referring to unity among groups in the new nation. Today, many learners are taught the more patriotic meaning: sacrifice, courage, and the blood shed by those who helped create and defend Mexico.