[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.

[5][6] The district's head town (cabecera distrital), where results from individual polling stations are gathered together and tallied, is Ciudad Obregón, the state's second largest city.

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.

It covered a part of that city, the rural part of its surrounding municipality, and the municipalities of Álamos, La Colorada, Mazatán, Onavas, Quiriego, Rayón, Rosario San Javier, San Miguel de Horcasitas, Soyopa, Suaqui Grande, Ures and Yécora.