Nueva Ecija's at-large congressional district
Nueva Ecija's at-large congressional district was the provincewide electoral district of Nueva Ecija for Philippine national legislatures before 1987. The district was first created ahead of the 1898 Philippine legislative election for two seats in the Malolos Congress. Epifanio de los Santos and José Turiano Santiago were elected at-large as Nueva Ecija's representatives in the National Assembly of the nascent First Philippine Republic, with a third seat allocated for an appointed delegate from Pampanga, Gregorio Macapinlac. After the fall of the Republic, the U.S. insular government was installed which  reorganized a legislative assembly for representatives of the different provinces in 1907, the Philippine Assembly. Nueva Ecija was given one seat in that legislature and continued to elect its representatives from this single-member at-large district until the 1926 reapportionment into two smaller districts which took effect beginning with the 1928 Philippine House of Representatives elections. Nueva Ecija returned to at-large elections for a seat in the National Assembly of the Second Philippine Republic in 1943. The restoration of the Commonwealth government and the House of Representatives in 1945 also restored the two districts in the province thereby  eliminating the provincewide electoral district. It was recreated for the last time ahead of the 1984 Philippine parliamentary election following a shift from regional electoral districts in the interim parliament, where Nueva Ecija was included in the multi-member at-large representation of Region III (Central Luzon) from 1978 to 1984, to provincial and city district constituencies in the regular parliament. The district became obsolete following the 1987 reapportionment that established four districts in the province under a new constitution.