The 20th federal electoral district of the State of Mexico (Spanish: Distrito electoral federal 20 del Estado de México) is one of the 300 electoral districts into which Mexico is divided for elections to the federal Chamber of Deputies and one of 40 such districts in the State of Mexico.

[1] It elects one deputy to the lower house of Congress for each three-year legislative session by means of the first-past-the-post system.

Votes cast in the district also count towards the calculation of proportional representation ("plurinominal") deputies elected from the fifth region.

[2][3] The 20th district was created by the 1977 electoral reforms, which increased the number of single-member seats in the Chamber of Deputies from 196 to 300.

Under the National Electoral Institute's 2022 districting plan, which is to be used for the 2024, 2027 and 2030 federal elections,[5] the 20th district covers four of the state's 125 municipalities: The district's head town (cabecera distrital), where results from individual polling stations are gathered together and tallied, is the city of Ojo de Agua, Tecámac.