Population change in a place = (number of births + number of in-migrants) – (number of deaths + number of out-migrants). A positive number means the population has increased by that number. A negative number shows that it has decreased by that number.

Assume for the moment that there is no migration. In order to calculate these increases we examine two rates. (1) Birth rate is the number of live births per thousand persons in a year. In 1992, the birth rate in India was 29. This means that for every 1000 people living in the country during that year, 29 live births took place. (2) Death rate is the number of deaths per thousand persons in a year. In the year 1992, for every 1000 persons living at that time, 10 people died during the year. Therefore, 19 people for every 1000 was the addition during the year. This number can be expressed as a percentage i.e. 1.9%. Hence, we say that the population growth rate was 1.9% for the year 1992.

The rate or the pace of population increase is important. It is studied in per cent per annum. For example a rate of increase of 2 per cent per annum means that in a given year, there was an increase of two persons for every 100 persons in the base year. This is calculated year by year like in compound interest. This is referred to as the annual growth rate. India’s population has been steadily increasing.

In order to examine the causes for the growth of Indian population, as seen from the graph above, we need to look at both death rate and birth rate. There has been a rapid decline in the death rate but till recent times, birth rate has not been decreasing substantially. The period 1901-21 witnessed high death rates due to famines, epidemics including influenza epidemic of 1918 that is estimated to have killed 15 million people. From 1921 onwards and especially post independence,