The electoral regions (circunscripciones electorales) of Mexico are geographic areas composed of various states used for the election of the 200 proportional representation legislators to the Chamber of Deputies.
Mexico is split into five separate regions. Each of the five regions elects 40 deputies, who are selected according to party lists in the regions. To distinguish them from those elected in the 300 single-member constituencies, they are often referred to as "plurinominal deputies".[1][2]
In contrast, the 32 senators-at-large elected to the Senate by the principle of proportional representation are drawn from party lists covering the entire country; the electoral regions therefore play no role in Senate elections.