Multiple choice general knowledge The world's longest earthen dam - Hirakud Dam, is in which state of India ? Orissa Madhya Pradesh Bihar West Bengal Reveal answer Fill a bubble to check yourself A Correct answer Explanation Hirakud Dam, built across the Mahanadi River, is located in Odisha (formerly known as Orissa). It is the longest earthen dam in the world and one of India's major multi-purpose projects.