Ballia (bŭl´yə), town (1991 pop. 84,758), Uttar Pradesh state, N central India. Situated on a rich alluvial plain, Ballia is a district administrative center and an important market for rice, sugarcane, and oilseed. There is some light industry. Changes in the course of the Ganges River destroyed the old town in the years from 1873 to 1877, and a new town was created in 1900. The annual Dadri fair, held on the full moon of Kartik (October–November) attracts about one million people.