Time in Mexico
In addition, the law dictates that all island territories should fall within the time zone corresponding to their geographic location.
Standard time was first defined in Mexico in 1921, when President
In 1930 three zones were decreed: Hora del Oeste (120° W) for the state of Baja California (norte); Hora del Golfo (90° W) covering the states of Tamaulipas, Veracruz, Oaxaca, Tabasco, Chiapas, Campeche, Yucatán and Quintana Roo; and Hora del Centro (105° W) for the rest of the country. 
It was decreed in 1942 that the Hora del Noroeste (105° W) should cover only the states of Baja California Sur, Sonora, Sinaloa, and Nayarit; while the Hora del Centro (90° W) was used for the rest of the country. 
The time zone Hora del Sureste (75° W) was created for tourist reasons in 1981, originally covering the states of Campeche, Yucatán, and Quintana Roo.  The three states returned one year later to the Hora del Centro (90° W);  Quintana Roo, however, returned to the Hora del Sureste (75° W) from October 1997 to August 1998 and then again in February 2015.