Agronomists have long suspected that within-row plant spacing uniformity has an impact on corn grain yield, but research and anecdotal evidence has been inconsistent at demonstrating this benefit. There is renewed interest in the concept of “picket-fence” plant spacing for several reasons. The first reason is the popularity of several planter calibration services that are currently being promoted across the Corn Belt. A second reason for this attention is the testimonials of corn yield contest winners that often insist that both adequate plant population and uniform spacing are necessary for top yields.