The decree of 1 August 1888 divided the Congo Free State into eleven districts, of which the first five were in the lower Congo region, including Stanley Pool District with its headquarters in Léopoldville.

[1] A map of the Congo Free State in 1897 shows the Stanley Pool District stretching along the east bank of the Congo River upstream from the Livingstone Falls past Léopoldville to just south of Lukolela.

The district was named after Stanley Pool, a widening of the Congo above Léopoldville.

[3] A major reorganization in 1914 adjusted boundaries and grouped the districts into provinces.

A 1926 map shows a new urban district of Léopoldville had been created around the capital city, and Moyen-Congo District had been merged into Bas-Congo (south) and Lac Léopold II (north).