[1] 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 third region.

[5][a] Under the 2017 scheme, the district covered 22 municipalities and had its head town at Pichucalco.

[6] In 2005–2017, the 4th district was located in the north-western portion of the state and covered the municipalities of Amatán, Berriozábal, Coapilla, Copainalá, Ixtacomitán, Ixtapangajoya, Juárez, Ocozocoautla de Espinosa, Ostuacán, Pichucalco, Reforma, San Fernando, Solosuchiapa, Sunuapa and Tecpatán.

It was still centred on Ocozocoautla de Espinosa but covered: 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.