The Papaloapan meanders for 122 km (76 mi) in a northeasterly direction through the coastal plain before draining into Alvarado Lagoon.

[3] The river basin covers 46,517 km2 (17,960 sq mi), the second largest in Mexico, and contains 244 municipalities with a population of about 3.3 million people.

[4] The cities of San Juan Bautista Tuxtepec and Tlacotalpan (Veracruz) are situated on the banks of the Papaloapan.

In the past the Papaloapan river basin was subject to frequent flooding, with the damage sometimes compounded by cyclones.

Construction of the Cerro de Oro Dam in 1989 on the Santo Domingo river reduced the extent of floods to a manageable level.