Three important developments in population studies took place in Europe and the United States in the nineteenth and twentieth centuries: the development of probability theory in statistics, the beginning of census operations and the establishment of the system of civil registration.
The United States of America had its first census in 1790 and England and France in 1801. As the census technique developed and improved, the scope widened, and more data became available. As the census was taken at regular intervals, it became possible to trace the course of population growth.
Much of the progress in the field of population studies in England may be attributed to the establishment of the General Register Office.
William Farr, who was appointed to this office in 1839 and who continued in that position up to 1880, contributed to the methodology of population analysis in many ways, notably by the construction of life tables and the study of occupational mortality.