The Central Valley is a plateau and a geographic region of central Costa Rica. The land in the valley is a relative plain, despite being surrounded by several mountains and volcanos, the latter part of the Central Range. The region houses almost three quarters of Costa Ricans, and includes the capital and most populous city, San José. The valley is shared among the provinces of Alajuela, Heredia, San José and Cartago. The region occupies an area of 11,366 km², more than a fifth of the country, and is drained by the Tárcoles River.