Historical and current datasets are primary sources and can be useful for shedding light on your topic. For example, statistics can include information on things like demographics (age, gender, race, ethnicity of a population at a given time), labor and employment, economics and consumer behavior, health and medicine, and more. Below are databases and other openly accessible sites where you can find these types of sources.

Library databases:

Openly accessible websites:

Polling information is a primary source because it is a measure of public opinion on a topic.  Databases and polling organization sites (such as Pew Trust and the Roper Center) provide poll data over a span of time on politics, consumer affairs, the environment, social issues, sports, and hundreds of other subjects. For more, see the Public Opinion Poll Data and Survey Resources Guide.