or Hooghly River River, northeastern India. The most westerly and commercially the most important arm of the Ganges River, it provides access to Kolkata (Calcutta) from the Bay of Bengal. Formed by the junction of the Bhagirathi and Jalangi rivers, it flows south about 160 miles (260 km) through a heavily industrialized area home to more than half of West Bengal's population. Above Kolkata the river is silted up, but it is navigable to the city by ocean liners. It enters the Bay of Bengal through an estuary 3-20 miles (5-32 km) wide, which is spanned by two bridges