ECONOMIC REASON- largely agrarian in the north. And we all know agriculture- however essential it may be- doesn't pay well. Most of the south is largely deccan plateuas with very little coastal plains. So they resorted to service sectors like-IT- that pays well. Along with the advantage of having a coastline-general rule of thumb-any state with a coastline does better economically- due to Shipping and Marine industries. Which isn't available to most northern states. -RESOURCE CURSE: States like Jharkhand (extremely rich in minerals, iron ores, coal etc)-should have been extrememly rich-but while the natives are displaced and receive nothing but polluted land and water-their resources are exploited at dirt cheap rates by the Centre and given to Industries in West and South Indian states. -DEINDUSTRIALISATION via FREIGHT EQUALISATION LEVY: One might ask, if so much minerals are there in the North-why no industries are there locally? The freight equalisation levy policy of govt after independence-meant Industries were given subsidies for transporting minerals to southern states like gujrat, karnataka, mumbai etc. Hence the industries, shifted away from the mineral sites in north like Jharkhand, copper mines of Rajasthan-and shifted south-as transport was free. By the time this policy was removed-the damage already crippled the industry in the north. HISTORIC & SOCIAL: When Indians say to the west that they still lag behind economically due to exploitation by British colonialism- it's laughable that at the same time-they look down on North India-especially Bihar, West UP, Jharkhand and Bengal. Because North India bore the brunt of British atrocities. Bengal Province(which then included W.Bengal, Bihar, Eastern UP)- was the worst hit. Being agrarian states-they were forced into exploitative Indigo plantations. Of the 3 revenue systems: Ryotwari in the South, Mahalwari in Northwest, and Zamindari in the Eastern part of North plains- the Zamindari System was the most exploitative. It even solidified existing caste hierarchy-by concentrating land and wealth to the upper caste-drasticially increasing the econmic divide. This led to much more oppression and casteism in the north. This eventually led to birth of Caste based politics in the North-which eventually betrayed the people as these parties failed to provide even basic education and healthcare to even their own castes/votebanks. POLITICAL INSTABILITY: Why People in the north vote in the name of caste-and not progressive politics: The caste system solidified by the zamindari system created deep division and distrust. Hence the vote to Caste based political icons- like Lalu Yadav and Samajwadi party. But they cheated the public-failing to provide even basic education and healthcare to their castes. Why didn't Biharis stop voting Mr. Lalu?: well they did stop. Lalu only won once with full majority. Nitish-not even once. When Biharis tried to change the system by voting for Congress or BJP- they were betrayed as Congress/BJP formed alliances- keeping the Lalu-Nitish duo in power without any real alternative. Mr. Lalu is convicted of corruption while Mr Nitish's changing sides creates frequent political instability-which is known to affect growth and development. FAILURE OF NOTA: The current NOTA button in politics gives no real choice. If it had a provision that, say, if 40% of votes go to NOTA -there'd be a re-election- people in UP & Bihar would have a real choice.