Electoral regions of Mexico Wikipedia
The electoral regions of Mexico (circunscripciones electorales) are geographic areas composed of various states used for the election of the 200 proportional representation legislators to the Chamber of Deputies.
Each of the five regions sends 40 deputies, which are selected according to party lists in the regions.
The electoral regions are divided to ensure a roughly equal distribution of population among the regions and may be modified by the National Electoral Institute. The current distribution has been in use since September 30, 2005.