Many doubt that partisan television’s audience is sufficiently large, persuadable, or isolated from cross-cutting sources for partisan television to meaningfully influence public opinion. However, limitations of survey-based television consumption measures have left these questions unresolved. We report findings from three novel datasets which each link behavioral measures of television consumption to political administrative or survey data. First, approximately 1 in 7 Americans consume over 8 hours/month of partisan television, outnumbering the US Black population; and approximately 1 in 4 Republican primary voters consume over 8 hours/month of Fox News. Second, consistent with selective exposure, about two-thirds of partisan television viewers are aligned partisans; however, weak partisans, independents, and outpartisans together represent over half of partisan channels’ audiences, suggesting much of its audience is persuadable. Finally, few aligned partisan television consumers also consume cross-cutting channels, consistent with partisan echo chambers. Partisan television’s polarizing potential cannot be easily dismissed.