Samastipur is a city and a municipal corporation (nagar nigam) in Bihar, India. It is the headquarter of Samastipur district and comes under Darbhanga division. The Budhi Gandak river flows through the town. It is one of the five railway divisions of ECR, Hajipur. The Samastipur junction is one of the busiest station in North Bihar after Patna and Katihar.