This study was designed to determine whether tillage systems left in place for significant periods of time develop different weed profiles. No-tillage, reduced tillage, and conventional tillage were placed in a corn/soybean rotation that had been maintained and documented for 15 years. Notillage was the only corn tillage treatment that did not lead yields for at least one year of this three-year trial. No-tillage corn had significantly higher weed pressure from several species, and soybeans had significantly higher levels of giant foxtail with no-tillage. The study also compared ridge and reduced tillage yields and weed profile development; the third year of the study constituted the eighth year that those systems were in place. Ridge tillage soybeans had higher yields and significantly higher weed pressure for a number of species; no trends were detected for corn yields or weeds.