Population is one of the few topics for which both historical and projection data are easily found online at no cost. Both sets of data are often found on the same site. Data can include total population, crude birth and death data, age and sex structure of populations, infant and under-5 mortality rates, etc. Some of the historical data goes back to 1950 while projections are often made to 2050 or 2100. The World Bank, the United Nations and the US Census Bureau are the main providers of free population data. A sample of total population data and projections for India and Swaziland is available here.
World Bank -- The World Bank has a number of databases with free population data available free online. Many of the databases can be accessed in more than one way, either through the common search facility or as Excel or CSV files which have been made up of selected indicators (Note that the preselected downloads often do not include all of the indicators in the database.) A main data page which gives access to the databases as well as a host of other information from the Bank is at http://go.worldbank.org/45B5H20NV0. However some users may find this page confusing. There are two main approaches to getting data, searching and downloading from the database or downloading the already prepared selection of data. The following databases which contain population data have a common interface for searching-- World Development Indicators (WDI) and Global Development Finance (GDF) (which have been combined for searching); Gender Statistics; Health and Population Statistics; African Development Indicators; and Millennium Development Goals. The search engine can be accessed directly at http://databank.worldbank.org/data/databases.aspx . Alternatively the same search possibilities as well as the prepared downloads are also available at http://data.worldbank.org/data-catalog which also provides access to a Gender Statistics database.
United Nations -- The Population Information Network at http://www.un.org/popin/data.html gives links to a number of population data sources, possibly the most interesting is World Population Prospects, the first set of links, which gives access to a download in .pdf format of a number of population tables as well as links to a data base ( http://esa.un.org/unpd/wpp/ ) with three searchable sites (panel 1, panel2 and country profile) which prepare reports for downloading in CSV formats -- searches can go back to 1950 and the site also provides population projections.
US Census Bureau --The US Census Bureau provides a wide range of materials including a downloadable database of demographic data including projections to 2050. The main page giving access to the various systems is http://www.census.gov/ipc/www/idb/ .
Gapminder -- Gapminder is an innovative data presentation web site which provides dynamic views of data changes over time using bubble graphs. Graphs are available for economic, population, health (including HIV/AIDS), environmental, agricultural and information technology data. Raw data can be downloaded from the site and a desktop version of the software is available free. Users can customize graphs using existing data, but cannot add new data. Much of the data used is from the World Bank and UN organizations. Gapminder is at http://www.gapminder.org .
UNFPA-- The United Nations Population Fund, publishes an annual report on the State of World Population. This report is available on their website at http://www.unfpa.org/swp/ . Previous reports starting with 1996 are available at from a link on the same page.
National Statistical Offices --A
list of links prepared by the United Nations to the websites of
National Statistical Offices and other providers of statistics at the
individual country level is available at
http://unstats.un.org/unsd/methods/inter-natlinks/sd_natstat.asp
and WTO also provides a list at http://www.wto.org/english/res_e/statis_e/natl_e.pdf
World Resources Institute -- The WRI provides free online data in EarthTrends. WRI provides a searchable time-series database with a range of indicators for more than 140 countries. Topics include Population, Health and Human Well-being. The searchable database permits searching for a single indicator but over a full range of countries and years. The result can be downloaded into csv format. The system also provides data tables and country profiles in pdf format, maps and feature stories. The database is available at http://earthtrends.wri.org/ . It is necessary to register to get access to some of the data, but registration is free.
World Population Resources--
Links to a large number of population sites are available at Learn
Stuff http://www.learnstuff.com/world-population-resources/ .
Population Pyramids -- this page provides links to instructions on creating population pyramids in Excel. For links click here.