During the course of the nineteenth century, the Registrar-General's Office in England and Wales used crude mortality rates as a demographic barometer of the environmental conditions of towns and cities. The local authorities in places with comparatively high rates were exhorted to improve them through more and better public health reforms. This technique of public coercion was often criticized, especially by a selection of Medical Officers of Health, who argued that crude death rates were an inaccurate measure of changing mortality levels and thus the success of preventive medicine. The debate over sanitary progress created no little tension between staff at the General Register Office and the Medical Officers, as well as between the Medical Officers themselves, at a time when public health doctors were seeking to properly establish themselves as a legitimate, professionalized branch within medicine. Despite this, the collection and dissemination of local mortality statistics became an indispensable component for the nineteenth century campaign to improve the nation's health.