The dramatic Democratic victories in the 2021 Georgia U.S. Senate runoffs handed Democrats their first majority since 2015 and, with this, unified Democratic control of Washington for the first time since 2011. While Democratic Leaders and President Joe Biden crafted their agenda, any hope of policy passage rested on complete unity in a 50–50 Senate and a narrow majority in the U.S. House. Against this backdrop, the 117th Senate is the most polarized since direct-election began in 1914 and, by popular accounts, the least deliberative in a generation. In this article, we examine the implications of partisan polarization for policymaking in the U.S. Senate throughout the direct-election era. First, we show that greater polarization coincides with more partisan Senate election outcomes, congruent with recent trends in the House. Today, over 90% of Senators represent states carried by their party’s presidential nominee. Secondly, we show that polarization coincides with higher levels of observable obstruction, conflict, partisan unity, and narrower majorities. Lastly, we show that this polarization coincides with lower levels of deliberation in the form of consideration of floor amendments and committee meetings. Taken together, we paint a picture of a polarized Senate that is more partisan, more obstructionist, and less deliberative.