The aim of this project was to analyse the changing geography of mortality decline in England and Wales between 1851 and 1911 via the cause of death by age data for registration districts published in the Registrar General's Decennial Supplements. 1851-1860 and 1861-1870 Mean population by registration district and sex, total deaths by registration district and sex, causes of death by registration district, sex and age group. 1871-1880 Mean population by registration district and sex, total deaths by registration district and sex, causes of death by registration district and age group, total marriages, total births. 1881-1890 and 1891-1900 Mean population by registration district and sex, total deaths by registration district and sex, causes of death by registration district and sex, causes of death by registration district and age group, total marriages, total births. Please note: this study does not include information on named individuals and would therefore not be useful for personal family history research.