Large areas of soils in the US Midwest require drainage for removal of excess water from fields early in the growing season. Few well-controlled studies have been done to quantify crop yield benefits from installing tile for drainage. This makes it difficult to document the long-term yield and economic benefits of tile drainage in on-farm conditions. Using digital aerial imagery and yield monitor technologies, we evaluated the long-term benefits of installing new or improving old tile drainage systems on Iowa corn yields. Three fields were selected for this study, each with a 5 to 10-yr history of recorded yield data and GPS. We used digital aerial imagery of the soil surface or the crop canopy to locate old and new tile. We then compared yields between tile and no-tile areas using at least three size-paired sampling areas in each field. Analysis showed that yield responses to new or improved tile systems increased over time, with the largest yield difference occurring in years when early season rainfall was above average. Using digital aerial imagery and yield monitoring data should help to better quantify yield and economic benefits of installing new and upgrading old tile drainage systems in production fields.