|Nickname(s): NRI city|
|Elevation||77 m (253 ft)|
|Time zone||IST (UTC+5:30)|
|Lok Sabha constituency||Siwan|
|Vidhan Sabha constituency||Siwan|
Siwan (the old name Aligunj) is located at  It has an average elevation of 77 metres (252 feet)..
As of 2011[update] India census, Siwan had a population of 3,318,176. Males constitute 50.4% of the population and females 49.6%. Siwan has a literacy rate of 72%, higher than the state average of 63.8%: male literacy is 82.8%, and female literacy is 60.4%. The literacy rate, hawever, is still below the national average of 74%. The literacy rate among males has risen considerably, but the females are still lagging far behind. Between 2001 and 2011, the sex ratio has fallen from 1031 females per thousand males to 984 females per thousand males. It is still higher than the national average of 940, but the sharp fall is a matter of concern.
The word "Siwan" means the border in Bhojpuri. Currently it is not located as border district of Bihar, India but formerly it was the southern border of Greater Nepal that's why it called "Siwan", the border. Dr. Rajendra Prasad (डॉ0 राजेन्द्र प्रसाद ) (December 3, 1884– February 28, 1963) was the first President of India.He was born in Zeradei, in the Siwan district of Bihar.
Rajendra Prasad was an independence activist and, as a leader of the Congress Party, played a prominent role in the Indian Independence Movement. He served as President of the Constituent assembly that drafted the constitution of the Republic from 1948 to 1950. He had also served as a Cabinet Minister briefly in the first Government of Independent India.
Deshratna Dr. Rajendra Prasad as long as he remained in Patna to lead the Freedom Movement. He lived and worked here since the establishment of Bihar Vidyapeeth on 6 February 1921
Dr. Rajendra Prasad- The first president of India, Dr. Rajendra Prasad belongs to Jiradeyi village, 8 km west of Siwan city. He was an independence activist and, as a leader of the Congress Party, played a prominent role in the Indian Independence Movement.
Maulana Mazharul Haque of Faridpur was also a great freedom fighter belongs to the SIWAN district
- Falling Rain Genomics, Inc – Siwan
- "Census of India 2001: Data from the 2001 Census, including cities, villages and towns (Provisional)". Census Commission of India. Archived from the original on 2004-06-16. Retrieved 2008-11-01.