The 64th Congress was noteworthy for its gender parity, with the most women ever elected to the Chamber of Deputies and Senate.

Women held 49 percent of the seats in the Senate, a national record and the third-highest percentage of women in a current national upper house, according to data collected by the Interparliamentary Union.

[1] The Chamber of Deputies had the fourth-highest percentage of women among lower houses.

[3] On 23 August the PRI, PRD, PAN and Movimiento Ciudadano announced they would challenge the allocation of proportional representation seats in the Chamber of Deputies, saying MORENA was overrepresented.

The Chamber of Deputies is composed of 500 seats, elected from 300 single-member federal electoral districts and 40 apiece from five proportional representation electoral regions.