The Radcliffe Line, the boundary between India and Pakistan was officially declared as the on 17th August 1947 following the Partition of India. It was named after Sir Cyril Radcliffe, the British lawyer who commissioned to draw the borders that would divide British India into two countries equally with 4,50,000 km sq of territory with 88 million people
He was asked to base his lines on the population of Muslims and Hindus and also to include economic and communication resources, such as irrigation channels and railway lines. This border resulted in one of the biggest human migrations in modern history, with roughly 14 million people displaced and over one million were killed.
For completing the borderline, Radcliffe travelled to Lahore and Kolkata to meet his Boundary Commission members including Jawaharlal Nehru representing the Congress and Muhammad Ali Jinnah representing the Muslim League.
Radcliffe completed the boundary line a few days before Independence, but due to some political reasons, the border was formally revealed two days after Independence. The line drew the border right down the middle of Punjab province, between Lahore and Amritsar.
So, the Punjabi and Bengali legislators were given a chance to vote on a potential split of the provinces and a plebiscite for or against joining Pakistan.