The government will launch the mammoth exercise of 2011 census on Thursday to cover 1.2 billion residents of the country living across 35 states and Union Territories. <br/><br/>The Home Secretary Mr. Gopal K Pillai said after completion of the exercise, the largest census to be attempted in the history of mankind, a National Population Register (NPR) will be created in which the government will have the entire population of the country under one database. He said that after the NPR is completed for the first time specific information about the entire usual residents of of the country will be available and the government will give a unique number to each usual resident of the country.<br/><br/>The Census operation, to be formally launched by President Pratibha Patil Census 2011 will be conducted in two phases. The first phase, called the Houselisting and Housing Census, will be conducted between April and July, depending on the convenience of different States and union territories.<br/><br/>This operation is to be conducted over a period of 45 days in each State and union territories.The second phase, called the Population Enumeration phase,will be conducted simultaneously all over the country from 9th to 28 the next year.<br/><br/>The Census would cover all 640 districts, 5767 tehsils, 7742 towns and more than 6 lakhs villages. More than 24 crores households will be visited and 1.20 billion people enumerated during this exercise. Twenty five lakh people will be engaged in the whole exercise.