[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.

[8][9] 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 Hermosillo.

[11] 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.

[12] The restored 5th district had its head town at San Luis Río Colorado and it covered 14 municipalities in the state's north-west: Altar, Atil, Benjamín Hill, Caborca, Carbó, Opodepe, Oquitoa, Pitiquito, Puerto Peñasco, San Luis Río Colorado, Santa Ana, Sáric, Trincheras and Tubutama.