Castellón ( ); ) is a province in the northern part of the Valencian Community. It is bordered by the provinces of Valencia to the south, Teruel to the west, Tarragona to the north, and by the Mediterranean Sea to the east. The western side of the province is in the mountainous Sistema Ibérico area. It has a population of 627,620. 30% of whom were residing in the capital, 60% in its metropolitan area, and 85% along the coastline. As of the 2011 Census, the population had grown to 594,423 people, but has since declined. The province, and in particular its idle large airport, has become a symbol of the wasteful spending prior to the 2008-14 Spanish financial crisis.
It is a bilingual territory whose inhabitants speak both Spanish and the local co-official language Valencian.
Other major cities of the province include Vila-real, Borriana, La Vall d'Uixó and Vinaròs. There are 135 municipalities in Castellón; see List of municipalities in Castellón.
Castellón is the home of Penyagolosa, the highest mountain of the province and the second highest one in the Valencian Community. It is widely considered to be one of the most emblematic Valencian mountains.
The Greenwich Meridian (the Prime Meridian) passes through the province; there are localities with commemorative monuments such as La Pobla Tornesa, Castellón or Almassora (Paseo Marítimo), and in Castellon it intersects the 40th parallel, and the exact point can be visited at the Meridian Park.
Comarques
The province is historically subdivided into the following comarques:
- Alcalatén
- Alt Maestrat
- Alto Mijares
- Alto Palancia
- Baix Maestrat
- Plana Alta
- Plana Baixa
- Ports
Demographics
As of 2025, the population of the province is 627,620, of whom 49.7% are male and 50.3% are female, compared to the nationwide average of 49.0% and 51.0% respectively. People under 16 years old make up 14.6% of the population, and people over 65 years old make up 20.3%, compared to the nationwide average of 14.0% and 20.7% respectively.