México·~130 millones
Mexico
El español más hablado del mundo. El estándar de facto del castellano americano para gran parte de los medios.
Pronunciation
Seseo (no /θ/). Clear, slightly slow pace, especially compared to Caribbean. Final 's' generally preserved (unlike Caribbean, Andalusian). The 'j' is fricative — more guttural than Castilian. Indigenous Nahuatl loanwords often have distinctive stress patterns (chocolate, aguacate, mezcal).
Grammar and register
Ustedes for both formal and informal plural — no vosotros, ever. The simple past (comí) is preferred over the perfect (he comido) for nearly all recent-past events. 'Le' as second-person formal: 'le acompaño' = 'I'll come with you (formal)'.
Distinctive words
all-purpose intensifier — wow / let's go / okay
“¡Órale, qué padre!”
cool / great (Mexican only)
“Está muy padre tu coche.”
cool (younger generations)
“Esa idea está chida.”
dude (extremely common)
“Oye wey, ¿qué hubo?”
work / job (informal)
“Tengo mucha chamba hoy.”
to drive (NOT 'conducir')
“Voy a manejar al super.”
computer (feminine, not 'ordenador')
“Se descompuso mi computadora.”
Context
Mexican Spanish has the largest single-country speaker base on earth — by population it's bigger than the entire Spanish-speaking population of South America combined. Most Spanish-language Netflix dubs and a huge chunk of US Spanish media use Mexican voice actors. If you only learn one Latin-American variant, this one travels the furthest.