The administrative district Sint-Niklaas was created in 1818, as a split-off from the district Dendermonde. The roots of the district are older, because they go back to the feudal castelanny Waasland, that did exist until 1795. And this castellany does have his roots in the Pagus Wasia (or "Land van Waas") (around 800, but probably older).
This pagus was, with the one of Gent, in the hands of a landlord Waltcaud. his sons and grand-son did become the first Counts of Flanders. 
The capital was and is the city Sint-Niklaas, although Lokeren did have far more inhabitants in the 19th century.
1818-1923The new district Sint-Niklaas was in 1818 composed os: Bazel, Belsele, Beveren-Waas, Burcht, Daknam, Doel, Eksaarde, Elversele, Haasdonk, Kallo, Kemzeke, Kieldrecht, De Klinge, Kruibeke, Lokeren, Meerdonk (created 1845), Melsele, Nieuwkerken-Waas, Rupelmonde, Sinaai, Sint-Gillis-Waas, Sint-Niklaas, Sint-Pauwels, Steendorp (created 1881), Temse, Tielrode, Verrebroek, Vraseene, Zwijndrecht.
1923-1976The municpalities Zwijndrecht and Burcht are transferred to the District Antwerp (Province Antwerp).
1977-nowThe administrative District Sint-Niklaas of the province East-Flanders is now composed of the following 7 municipalities:
- Waaslanders who emigrated in 1903 (Statistics)
- Waasland Families by Harry Truyman
- 5 centuries and more of Truyman Families in Waasland and Zeeland by Albert Truyman (Dutch)
- Waasland Families by Jean-Pierre Van Eygen