[2] Its population is 185,531 (2021), and its area is 6,048.4 km2 (2,335.3 sq mi).

[3] Its surface area of over 6,000 km2 is the largest of any arrondissement in Metropolitan France, its size being comparable to an entire département such as the Eure.

The communes of the arrondissement of Mont-de-Marsan, and their INSEE codes, are:[2] The arrondissement of Mont-de-Marsan was created in 1800.

[4] As a result of the reorganisation of the cantons of France which came into effect in 2015, the borders of the cantons are no longer related to the borders of the arrondissements.

The cantons of the arrondissement of Mont-de-Marsan were, as of January 2015:[5]