Time in Mexico
- Zona Sureste (Southeast Zone) covers the state of Quintana Roo (the equivalent of Canadian and U.S. Eastern Time).
- Zona Centro (Central Zone) covers the eastern three-fourths of Mexico, including Mexico City (the equivalent of Canadian and U.S. Central Time).
- Zona Pacífico (Pacific Zone) covers the states of Baja California Sur, Chihuahua, Nayarit, Sinaloa, and Sonora (the equivalent of Canadian and U.S. Mountain Time).
- Zona Noroeste (Northwest Zone) covers the state of Baja California (the equivalent of Canadian and U.S. Pacific Time).
In addition, the law dictates that all island territories should fall within the time zone corresponding to their geographic location.
President Gral. Álvaro Obregón decreed the existence of two time zones in 1921: One time zone designated 90° W covering the states of Tabasco, Chiapas, Campeche, Yucatan, and Quintana Roo. A second time zone designated 105° W covering the rest of the country, from Baja California to Veracruz and Oaxaca.
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, Yucatan 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, it originally covered the states of Campeche, Yucatan, and Quintana Roo. The states of Campeche and Yucatan returned one year latter to the Hora del Centro (90° W); while Quintana Roo returned to the Hora del Sureste (75° W) in 2015.
Daylight saving time
First observation of DST was in 1931, but only for the state of Baja California. It used the "Hora del Centro" from April 1st to September 30th, and the "Hora del Oeste" the rest of the year. Until 1996, Baja California was the only Mexican state to observe DST, coinciding with the observance of DST across the border in San Diego, California.
Daylight saving time has been observed in Mexico beginning in 1996. Except for the municipalities located less than 20 km from the US border, it does not coincide with the longer extended daylight saving period adopted for 2007 in the United States. Rather, the federal law dictates that daylight saving time be observed between 2 a.m. on the first Sunday in April through 2 a.m. on the last Sunday in October.
As the United States now starts DST on the second Sunday in March and ends it on the first Sunday in November, Mexico's time zones are now out of synchronization with American and Canadian time zones for two periods each year. The first is the three or four weeks between the second Sunday in March and the first Sunday in April. The second is the single week between the last Sunday in October and the first Sunday in November. During these periods, clocks in Mexico City match those in Denver rather than those in Chicago. The Mexican Stock Exchange changes its hours during these periods in order to maintain synchronization with the U.S. markets.
In 1998 the state of Chihuahua moved from Central time to Mountain time. This is likely because Ciudad Juárez is directly across the border from El Paso, Texas, which is on Mountain Time. Later in 2001 Mexico experimented with a shorter daylight saving period from the first Sunday in May till the last Sunday in September. The areas that border the United States began observing DST on the US schedule in 2010.
Daylight saving time is observed in all parts of the country except for the state of Sonora, which decided to remain on standard time beginning in 1999. This is to coincide with the non-observation in Arizona, with which Sonora shares its northern border. The island territories do not currently observe daylight time either. During DST period, Mexico uses 4 different time zones.
IANA time zone database
|c.c.*||coordinates*||TZ*||comments*||UTC offset||UTC offset DST||Notes|
|MX||+1924-09909||America/Mexico_City||Central Time - most locations||−06:00||UTC-05:00|
|MX||+2105-08646||America/Cancun||Central Time - Quintana Roo||−06:00||UTC-05:00|
|MX||+2058-08937||America/Merida||Central Time - Campeche, Yucatan||−06:00||UTC-05:00|
|MX||+2540-10019||America/Monterrey||Mexican Central Time - Coahuila, Durango, Nuevo Leon, Tamaulipas away from US border||−06:00||UTC-05:00|
|MX||+2550-09730||America/Matamoros||US Central Time - Coahuila, Durango, Nuevo León, Tamaulipas near US border||−06:00||UTC-05:00|
|MX||+2313-10625||America/Mazatlan||Mountain Time - S Baja, Nayarit, Sinaloa||−07:00||UTC-06:00|
|MX||+2838-10605||America/Chihuahua||Mexican Mountain Time - Chihuahua away from US border||−07:00||UTC-06:00|
|MX||+2934-10425||America/Ojinaga||US Mountain Time - Chihuahua near US border||−07:00||UTC-06:00|
|MX||+2904-11058||America/Hermosillo||Mountain Standard Time - Sonora||−07:00||-|
|MX||+3232-11701||America/Tijuana||US Pacific Time - Baja California near US border||−08:00||UTC-07:00|
|MX||+3018-11452||America/Santa_Isabel||Mexican Pacific Time - Baja California away from US border||−08:00||UTC-07:00|
|MX||+2048-10515||America/Bahia_Banderas||Mexican Central Time - Bahía de Banderas||−06:00||UTC-05:00|
On 2010-01-06 a zone America/Ensenada named for Ensenada, Baja California was scheduled for inclusion with the comment "Split off Mexican cities (near US border) that are to follow US rules starting in 2010. Tijuana splits into ETijuana and Ensenada". 
- "Quintana Roo estrena nuevo horario mañana". El Universal (in Spanish). 31 January 2015. Retrieved 1 February 2015.
- Mexico City time changes in 1996
- Northern Mexican Border's New Daylight Saving Plan
- National Commission for the Conservation of Energy
- Chihuahua time changes in 1998
- Mexico City time changes in 2001
- Hermosillo time changes in 1999