[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] Under the National Electoral Institute's 2022 districting plan, which is to be used for the 2024, 2027 and 2030 federal elections,[4] the 1st district covers five of the state's inland municipalities: Colima, Comala, Coquimatlán, Cuauhtémoc and Villa de Álvarez.

The district's head town (cabecera distrital), where results from individual polling stations are gathered together and tallied, is the state capital, the city of Colima.

[1] As under the 2022 plan: the five municipalities of Colima, Comala, Coquimatlán, Cuauhtémoc and Villa de Álvarez.