Using GPS devices and digital cameras, we surveyed outdoor advertisements in Austin, Los Angeles and Philadelphia. GIS and hot spot analysis revealed that unhealthy ads were clustered around child-serving institutions in Los Angeles and Philadelphia but not in Austin. Multivariate generalized least square (GLS) regression models showed that percent black (p<0.04) was a significant positive predictor of clustering in Philadelphia and percent white (p<0.06) was a marginally significant negative predictor of clustering in Los Angeles after controlling for several land use variables. The results emphasize the importance of zoning and land use regulations to protect children from exposure to unhealthy commercial messages, particularly in neighborhoods with significant racial/ethnic minority populations.