In this paper, I examine the systemic effects of campaign spending, looking at outcomes at the level of the legislature rather than the individual seat. Using a difference-in-differences design, I show that state-level corporate campaign contribution bans have a large effect on electoral outcomes at the legislature level. A 1 percentage-point increase in the Democratic (or Republican) party’s share of all contributions in an electoral cycle is estimated to increase its share of the legislature by roughly half a percentage point. Policy outcomes as well as campaign finance reforms occur at the legislature level; understanding the systemic rather than individual-level effect of campaign spending is therefore directly relevant. Aggregating estimated effects of individual-level campaign finance would not produce this same estimate owing to spillovers and other strategic dynamics. Taken together, the analyses suggest that contribution bans have important electoral effects and thus point to the systemic effects of campaign spending.