Samastipur is a district in Bihar which is spread over an area of 2904 sq. kms. It is spread over an area of 2904 sq. kms. Samastipur is bounded on the north by the Bagmati River which separates it from Darbhanga district. On the west it is bordered by Vaishali and some part of Muzaffarpur districts, on the south by the Ganges, while on its east it has Begusarai and some part of Khagaria districts. The district headquarters is located at Samastipur.

People of Samastipur mainly speak Hindi. According to the 1991 census, Population Density in the District was 935 per sq.km. and the total population was 2.72 million.

The District is lacking in its educational infrastructure and the Literacy rate is only 36.37 % (male 50.39, female 21.17). The medical facility is also significantly low but there are efforts taken to improve the condition.

The district comprises of 4 sub-divisions, and 14 Community Development Blocks. It has 5 towns and 1237 villages. Infrastucture wise Samastipur is very strong. It is the Divisional Headquarters of the North Eastern railway. The district has direct train link with Patna, Kolkata, Delhi, Dhanbad, Jamshedpur and other places of importance. National Highway No. 28 passes through the district.

Agriculture is the main economic occupation of the district and about 83 per cent of the total working population depends on it. Samastipur is noted for its fertile alluvial soil and its rabi crops. It has been the center of the indigo industry. Wheat, pulses and edible oil seeds are also grown here. Samastipur is lucky to be traversed by rivers like Burhi Gandak, Baya, Kosi, Kamla, Kareh and Jhamwari and Balan, which are both the offshoots of Burhi Gandak. The Ganges also skirts the district on the south.