During the late 90s, research in the northern Corn Belt comparing 15- and 30-inch row corn illustrated yield benefits to narrow rows. In addition, many Iowa producers found soybean yields were optimized when soybean row widths were decreased below 30-inches. As a result, Iowa producers questioned whether benefits to narrow row corn (< 30 inches) existed in Iowa. To answer these questions, research was conducted to evaluate the effect of row spacing and related planting decisions on the yield of modern high-yielding corn hybrids. During the 1997, 1998, and 1999 growing seasons, the effects of row width and harvest plant density were evaluated. The objective of the study was to identify the optimum plant density for corn planted in 15-inch rows compared with 30- inch rows. In addition to this site, this study was conducted on five other university research farms.