Statistical data is important for studying the US government, specifically in the social sciences.
The Constitution stipulates that a Decennial Census is conducted in order to establish the population in each state. This is to feed into the calculations to establish the number of Congresspeople per state who sit in the House of Representatives. As history progressed, the Decennial Census grew wider in scope and became more than a population count, providing information on employment, demographics and more.
In 2005, data previously collected in the decennial census was collected in the American Community Survey. This survey is run yearly, and includes data on social, economic, demographic and housing information. This data can be used by American business owners and local governments when planning new resources/businesses. You can find out more about the differences between the ACS and the decennial census on the Census Bureau's website, alongside other surveys conducted by the Bureau.
The below report suggests some resources related to Census and Election data, alongside some other data sources.