Because Mexico is not the same as the US state of New Mexico. It is an independent country with a developing economy and has Mexico City as its capital.
Mexico is a country, but the capital of Mexico is Mexico city.
In the country of Mexico.
Mexico.
Mexico City is the capital of Mexico (the country).
Mexico City is IN Mexico; it is the capital of such country.
Mexico (Mexico City)
Mexico City is capital of the country of Mexico.
The country of Mexico.
Mexico
"Mexico" is the name of a city, a state and a country.
It is Mexico City; and it is in Mexico, the Country.
Urbanization in mexico city is at it's peak. It is a sentence using the word urbanization in Mexico city.