Historical primary sources online: Aggregate data
Aggregate data sources can be data-discovery tools
Some sources of aggregate data provide only tables and source information, leaving the original microdata out of sight. Online, it is common for tables to be exportable in CSV or other delimited formats so they can be combined in new tables or maps; it's sometimes possible to combine or query variables directly online. Larger providers permit bulk downloading of their data via application programming interfaces (APIs). For repositories of microdata, see the research datasets tab.