The BJP has won absolute majority in Rajasthan and Madhya Pradesh and is the single-largest party though shy of a clear majority in Delhi, where Arvind Kejriwal's Aam Aadmi Party has ensured, in a stunning debut, that the ruling Congress stands decimated. (Track live updates)
In Chhattisgarh, the BJP and the Congress ran neck and neck all day. But a late evening surge helped the BJP end up with a clear majority. With this, it wrapped up the day 4-0. (Read)
The Congress's bruising defeat underlines the struggle it will face to cling to power in the national election due by May. It has led the central government for two terms and is facing widespread voter anger over corruption, slowing growth and stubborn inflation.
Congress president Sonia Gandhi accepted the result "with humility" and prescribed "deep introspection" for her party. The BJP's Rajnath Singh said the result was an emphatic rejection of the Congress.
"The Congress's tally of seats in all four states put together is less than the BJP's seats in either Rajasthan or Madhya Pradesh," he noted.
In Rajasthan, the BJP's Vasundhara Raje will be Chief Minister, having evicted the Congress's Ashok Gehlot with one of the most outstanding electoral performances of recent times, winning 162 seats of the state's 200 seats. (Read: Narendra Modi a big factor in Rajasthan win, says Vasundhara Raje)
In Madhya Pradesh, Shivraj Singh Chouhan bettered his own performance of last time and won 165 of the 230 seats and a third straight term as Chief Minister.
In Delhi, the Aam Aadmi Party is the big story. It ended the day with 28 seats, just four short of the BJP's 32. Delhi has 70 assembly seats. Arvind Kejriwal has defeated three-time chief minister Sheila Dikshit in her constituency, New Delhi, by an enormous margin. (Read)
The Congress's Rahul Gandhi acknowledged that there was a lesson to be learnt from the Aam Aadmi Party phenomenon. (Read)