Natalicio de Benito Juarez (Birthday of Benito Juarez) was originally March 21.
Observance: This national holiday is observed on the third Monday of March.

March 21st is the birthday of one of Mexico’s great presidents. An important statesman and liberal reformer, Benito Juarez was the first and only full-blooded indigenous leader to serve as president of Mexico. Born in 1806 in the village of Guelatao, Oaxaca, he studied for the priesthood before choosing to pursue a career in law. His image has been use on two Mexican Bank Notes.

More info here:  Natalicio de Benito Juarez, Birthday of Benito Juarez
www.eventsloscabos.com/2013/03/natalicio-de-benito-juarez-birthday-of-benito-juarez/

Statutory holiday:
Holidays observed nationwide. Employees are entitled to a day off with regular pay and schools (public and private) are closed.