Abstract
In the months before the 2020 U.S. election, several political campaign websites added prechecked boxes (defaults), automatically making all donations into recurring weekly contributions unless donors unchecked them. Since these changes occurred at different times for different campaigns, we use a staggered difference-in-differences design to measure the causal effects of defaults on donors' behavior. We estimate that defaults increased campaign donations by over $43 million while increasing requested refunds by almost $3 million. The weekly default only impacted weekly recurring donations, and not other donations, suggesting that donors may not have intended to make weekly donations. The longer defaults were displayed, the more money campaigns raised through weekly donations. Donors did not compensate by changing the amount they donated. We found that the default had a larger impact on smaller donors and on donors who had no prior experience with defaults, causing them to start more chains and donate a larger proportion of their money through weekly recurring donations.