On Fri, Oct 9, 2015, at 02:37, L. David Baron wrote:
The best I could find at the Centro Nacional de Metrología was this: http://www.cenam.mx/hora_oficial/ndisposicion.aspx which first quotes from a decree that lists a smaller list of municipalities, and then gives a broader rule that says all municipalities within 20km of the US border *plus* the municipality of Ensenada in Baja California follow the US rules.
That page says "la Ciudad de" Ensenada, which may mean the city (125 km from the border) rather than the municipality (which covers the whole rest of the state) It might be best to simply see if someone can contact a business in, say, San Felipe, and find out what time it is. If they do use the Mexican rule, they're probably the largest (and furthest north of any significant size, at 190 km from the border) city in the state that does.
(I'd caution that my Spanish is reasonably good, but not the level of a native speaker. Probably better than Google Translate, though.)
I wonder if there are subtleties we are missing that mean this is a list of municipalities in which *at least part of* the municipality observes US rules.