Préfecture (capital): Cergy[?]
Sous-préfectures: Argenteuil[?], Montmorency[?] and Pontoise[?].
List of Communes of the Val-d'Oise département of France
... the age of 18, 9.6% from 18 to 24, 30.3% from 25 to 44, 20.9% from 45 to 64, and 9.8% who are 65 years of age or older. The median age is 34 years. For every 100 females ...