India, March 6 -- Nitish Kumar, Bihar's longest serving chief minister, filed his nomination papers for the Rajya Sabha on Thursday. This amounts to his de facto resignation as the chief minister of the state. The next chief minister will perhaps be from the Bharatiya Janata Party (BJP), the senior partner in the National Democratic Alliance (NDA) in the state. Kumar moving on as Bihar's chief minister is one of the most important milestones in the state's political history since independence. What did Nitish Kumar's 20 plus years mean for the state, its politics, economy and society? Here are three charts which answer this question.

HT's database of chief ministers has 23 unique chief ministers in Bihar from its first, Shri Krishna Sinh...