Corn growers in the US and elsewhere are constantly evaluating conventional and emerging agronomic practices that will enhance the productivity, profitability and sustainability of their crop production systems. Modifying corn row spacing and plant configuration is one such management practice. In recent years, the dominant corn row spacing choice in the US has been 30 inch-spacing between single planted rows (>80% in the US). Conversion from the standard 30-inch row spacing to either narrower rows or twin rows has gained considerable attention but limited adoption. Proponents of the various  row spacing choices that result in more equidistant plant spacing have cited several potential agronomic benefits, including less plant-to plant competition, greater light interception and a greater compatibility with ever-increasing plant populations that are recommended for today’s hybrids. A review of the literature indicates no consistent yield advantage for twin row over 30-inch single row production and no effect of site yield level. However, row spacing research is easily confounded and the increased attention that twin and 20-inch row production systems are currently receiving is probably justified. In theory, the greatest benefit of twin- or narrow- row production would be expected where, 1) the row-spacing currently exceeds 30-inches, or 2) in the Northern Corn Belt (north of I-90) where more rapid canopy development and subsequent greater light interception is advantageous during the shortened growing season. More recent comparisons of twin- and single-row production have also been inconsistent, although advantages for twin rows may indeed be greater with hybrids that have optimum plant populations above 38- to 40,000 plants per acre. Ultimately, the row spacing choice that any corn grower selects must optimize a variety of farm-specific agronomic, equipment, flotation/compaction, irrigation, guidance, field access and cropping considerations.