Campaign ads intended to win competitive states often spill into noncompetitive areas. Analyzing contribution data from Wisconsin alongside ad exposure information, this study finds that zip codes exposed to political ads saw an average increase of $6,100 (28.1%) in total donations compared to similar unexposed zip codes during the 2008 election cycle.

### Data & Methods

Spillover effects were examined using data from the Wisconsin Advertising Project and campaign contribution records compiled by the Federal Elections Commission for the period leading up to the 2008 presidential election. Propensity score matching techniques identified control groups of zip codes that mirrored exposure conditions but lacked ad presence.

### Key Findings

Exposure to political ads in noncompetitive states correlates strongly with higher levels of aggregate campaign giving:

* Ads in uncontested regions increased total contributions by approximately $6,100 on average (representing a 28.1% increase).

* This effect occurred despite candidates not intending these areas as primary targets.

### Why It Matters

These findings reveal the unintended consequences of campaign advertising strategies:

* Spillover exposure may significantly influence fundraising outcomes even in noncompetitive states.

* Candidates' ad choices have implications beyond their direct electoral competition, potentially affecting overall campaign finances.