[1][a] It elects one deputy to the lower house of Congress for each three-year legislative period 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 fourth region.

The 1st district had its head town at Ciudad Altamirano and it comprised 16 municipalities: Coyuca de Catalán, Ajuchitlán, San Miguel Totolapan, Apaxtla, Cuetzala del Progreso, Teloloapan, Ixcateopan, Pedro Ascencio Alquisiras, General Neri, Arcelia, Tlapehuala, Tlalchapa, Cutzamala, Pungarabato and Zirándaro (all included in the 2022 plan), plus the municipality of Cocula.

The 1st district covered 12 municipalities in the north-west of the state: Ajuchitlán del Progreso, Apaxtla, Arcelia, Coyuca de Catalán, Cutzamala de Pinzón, General Heliodoro Castillo, Leonardo Bravo, Pungarabato, San Miguel Totolapan, Tlalchapa, Tlapehuala and Zirándaro.

[9][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.