[1][a] 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 third region.

Veracruz lost a congressional district in the National Electoral Institute's 2022 redistricting plan, which is to be used for the 2024, 2027 and 2030 elections.

[2] Between 2005 and 2017 the 18th district had its head town at Zongolica and it comprised 24 municipalities in the same region as the later schemes: Acultzingo, Astacinga, Atlahuilco, Camerino Z. Mendoza, Coetzala, Cuichapa, Cuitláhuac, Huiloapan de Cuauhtémoc, Magdalena, Mixtla de Altamirano, Omealca, Rafael Delgado, Los Reyes, San Andrés Tenejapan, Soledad Atzompa, Tehuipango, Tequila, Texhuacan, Tezonapa, Tlaquilpa, Tlilapan, Xoxocotla, Yanga and Zongolica.

[11][10] The districting scheme in force from 1978 to 1996 was the result of the 1977 electoral reforms, which increased the number of single-member seats in the Chamber of Deputies from 196 to 300.