This dataset is an aggregation of county-level tillage practices to the 8-digit hydrologic unit watershed. The original county-level data were collected by the Conservation Technology Information Center (CTIC) and is a proprietary dataset. The CTIC collects tillage data by conducting surveys about tillage systems for all counties in the United States. Watershed aggregations were done by overlying the 8-digit HUC polygons with a raster of county boundaries and a raster of the 1992 enhanced National Land Cover Data for land use 61, 62, 82, 83, and 84 (cultivated land) to derive a county/land-use area weighting factor. The weighting factor was then applied to the county-level tillage data for the counties within each 8-digit HUC and summed to yield the total acreage of each tillage type within each 8-digit HUC watershed. Tillage systems include three types of conservation tillage (no-till, ridge-till, and mulch-till), reduced tillage, and intensive tillage. Total planted acreage for each tillage practice for each crop grown is reported to the CTIC.The dataset includes total planted acreage by tillage type for selected crops (corn, cotton, grain sorghum, soybeans, fallow, forage, newly established permanent pasture, spring and fall seeded small grains, and "other" crops) for 1989-2004. The CTIC did not collect data nationwide for 1999, 2001, and 2003. In addition, data were not collected for all counties every year. Missing data are coded with -9999. The companion WBDHUC8 geospatial dataset is available online: https://water.usgs.gov/lookup/getspatial?wbdhuc8.xml .