Cinco de Mayo is not a federal public holiday throughout Mexico.
The date commemorates the Mexican victory at the Battle of Puebla on May 5, 1862, but it does not generally produce a nationwide day off from work. Public observance is particularly strong in Puebla, where the battle occurred, and schools or local institutions may hold commemorations.
This differs from Mexico’s Independence Day on September 16, a nationwide public holiday with broad official celebrations. Cinco de Mayo’s much larger profile in the United States can therefore create the mistaken impression that it is Mexico’s principal national holiday.
In the United States, the date has become associated with Mexican-American heritage, public festivals, music, food, and commercial events. Those modern celebrations do not change its legal status in Mexico.