Association of Religion Data Archives (ARDA)
The ARDA contains many datasets pertaining to religion, such as surveys on topics such as the public's religious attitudes and practices, surveys of church leaders, and studies on the provision of social services by individual congregations. ARDA also provides national profiles of religious populations, religiosity, and religious freedoms/restrictions.
International Data Base
The International Data Base (IDB) is a computerized data bank containing statistical tables of demographic and socio-economic data for 227 countries and areas/regions of the world. The data available here cover topics such as fertility and birth rates, population breakdowns by sex and age, and migration. Historical data and projections out to 2025 or later are available.
World Population Prospects
This database is produced by the United Nations' Population Division and contains cross-national data on basic population demographics and vital statistics (e.g. birth and death rates, maternal mortality, population by age and gender and urban/rural areas, median age of population). Data are available in five-year increments back to 1950 and with projections up to 2050.