[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 first 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] Sonora's 4th district comprises 41 municipalities in the central and eastern parts of the state:[5][6] The district's head town (cabecera distrital), where results from individual polling stations are gathered together and tallied, is the port city of Guaymas.

[7] Under the 2005 plan, the district's head town was at Guaymas and it covered 39 municipalities.

[10][9] 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.