How were borders between Pakistan and India demarcated?

Few weeks before the Britishers were going to leave the Indian subcontinent, a British lawyer Sir Cyril Radcliffe was commissioned to demarcate the borders between Pakistan and India on the basis of religious demographics, following the Parliament of the United Kingdom passed the Indian Independence Act 1947.
Under the rule set for the division, Muslim-majority provinces had to annex to Pakistan and Hindu and Sikh-majority provinces to India.
There were also “other factors” on the basis of which the borders were drawn other than population and those factors were never defined.
The boundary line demarcated by the British lawyer was known as the Radcliffe Line and it was officially announced on August 17, 1947, two days after the creation of Pakistan and India into separate lands. This resulted in the biggest migrations in the history of mankind as about 14 million people were displaced and over a million others were killed. 4,50,000 km sq of territory was divided with 88 million people.

According to Maps of India (MoI) website, prior to the partition, 40 percent of India comprised of princely states which were not governed by the British rulers. The rulers of these states were free to choose from both the countries.
Balochistan, Sindh and the North West Frontier Province (now Khyber Pakhtunkhwa had clear majority of Muslim population. But the provinces of Punjab (55.7% Muslims) and Bengal (54.4% Muslims) were not made parts of Pakistan on the ground that they did not have an overpowering majority of Muslims, instead they were further divided into Pakistani Punjab and Indian Punjab and Pakistani Bengal and Indian Bengal.

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Punjab
Punjab had scattered population of different communities, therefore it was decided that a line would be created which could minimize the number of relocations and losses.
First foreign minister of Pakistan and Muslim League leader Muhammad Zafarullah Khan had said that the line in Punjab was drawn much to the prejudice of Pakistan.

Gurdaspur district
According to the 1901 census, the population of Gurdaspur district comprised of 49% Muslim, 40% Hindu and 10% Sikh. While, at the time of partition it had more than 51 percent Muslim population. Last viceroy of India Mountbatten had allegedly in connivance with Nehru pressurized Radcliffe to award the district to India. This district had four tehsils and only Shakargarh tehsil which was separated with others by Ravi river towards west was given to Pakistan.
It is believed that India was given the other three tehsils as this district was the only route which could connect India with Kashmir and India forces had entered the Himalayan territory through the same route.

Working Boundary, Line of Control and International Boundary
The border between the neighbouring countries is internationally recognized except for the Line of Control (LoC). The valley of Jammu and Kashmir was divided into Pakistan-administered areas and Indian-administered areas in 1949 and their boundary is known as the LoC.
The border along Pakistan’s Sialkot and Indian-administered Kashmir is called the Working Boundary as on the one side it is an internationally recognized land, while on the other is disputed territory.
