Prior research has shown that Citizens United—which legalized unlimited independent expenditures by corporations—has shifted public policy in a more conservative, pro-business direction. We argue that Citizens United has had an even deeper impact by contributing to recent democratic backsliding in the United States. Using a state-level difference-in-differences design, we find that Citizens United (which forced 23 states to remove pre-existing limitations on independent expenditures while leaving the other 27 states untouched) led to a significant decline in the freeness and fairness of state elections. This effect is attributable to Citizens United tipping several close elections in favor of Republicans just before the 2010 redistricting cycle, enabling extensive Republican-led gerrymandering and voter suppression—anti-democratic institutional changes that largely persist to this day. Our study is the first to empirically establish a direct connection between money in politics and democratic backsliding.