As the first national Census of independent India began on February 9, 1951, the chief minister of Assam, BR Medhi, addressed an army of enumerators in the state:
  “You have the proud privilege and unique honour of taking a very important part of collecting the data during the Census operation to enable the Nation to know its problems and prepare a plan for their solution of the basis of such data. I may also tell you that the first National Register of Citizens of the Republic of Bharata will also be prepared from the data collected by you during this Census operation.”  
According to RB Vaghaiwalla, the Indian Civil Service officer who was superintendent of Census operations in Assam, Manipur and Tripura, not all enumerators were convinced it was a proud privilege. “The reaction of Supervisors and Enumerators on appointment was one of general reluctance to accept,” he writes in his administrative report on Census operations.
Still, thousands of enumerators were put to work over the next 20 days, instructed to finish their task by sunrise on March 1, 1951.
The Census had been a regular feature of Indian life under the British since the 1870s, its data collection encompassing the entire population, regardless of nationality and citizenship. But the National Register of Citizens was a new initiative.
It did not require the surveyors to collect fresh data – all they had to do was transfer data from the Census slips into what would become the NRC.