Get on Google Maps or one of the other search engine maps... maybe Bing. Look at Mexico. Look at the United States. Both of them are shown as separate units. But both of them are shown as being broken into many smaller units.
In different ways both of them are broken into many units. Sometimes the units match the formal "google" states. Other times cities mean more than the states. The point?
The point is the values. The government of Mexico is weaker with relation to its inner divisions than the US is in relation to ITS inner divisions. The reason(s)? Mexico's values aren't built into its foundational governmental writings in the same way that values are built into the US foundational government writings.
I don't know which is better for the people living there, but the Mexico government allows for more freedom for its people. How? Corruption in government is more easily achieved, so the people are often simply ignored if they don't, individually, make a big stink about something. Government people are too busy fighting among themselves. Sure, the people are poor. But they are free among themselves.
So, it isn't surprising that they form their own governments among the cartels and in other ways.
In the US, the strength that the people have to use their government to fight government corruption, usually keeps that corruption to a minimum (sort of). So, US people are more easily united under their government to remain free thereby. It's this freedom that has made them lax, so the people don't see how government corruption is on the verge of taking them over.
However, the US has its divisions in the militia, and in other ways. Fed Gov corruption is about to be controlled by the people in the US... if the people act in a timely manner.