Prior to 1921, the course of population growth was undulating (several ups and downs, mainly because of mortality differentials). During 1911-1921, India experienced negative growth rate in her population. After 1921, Mortality started declining as a result of improvement in public heath measures while, fertility remained unchanged which caused a continuous and rapid increase in population growth rate in upcoming decades. Hence, 1921 was the year when India moved from stage 1 to stage 2 of demographic transition. Therefore, year1921 is known as the year of the great divide in the demographic history.