A large number of polls providing data on public opinion of political and sporting issues.

A non-partisan public opinion polling organization.

Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping America and the world. It conducts public opinion polling, demographic research, media content analysis and other empirical social science research.

The New York Times' data analysis section, The Upshot, provides probabilities of winning for each candidate in each state, updated daily.