Delta and Pine Land Company field size variety test plots with plant map data were conducted at 110 locations from Arizona to North Carolina during 1994 and 1995. Variability in growth and earliness factors were partitioned into that due to locations (environment), varieties, or error by maturity test, region, and year. Averaged over maturity test group, regions, and years, the ratio of location: variety was 3.0 for the number of vegetative nodes to the first fruiting branch; 6.9 for percent retention of the bottom five first position bolls; 6.7 for average retention of all first position bolls in the zone that held 95 percent of all harvestable bolls (the 95% zone); 5.1 for the node number of cutout; 7.6 for final plant height; 7.5 for final number of nodes; and 4.2 for height to node ratio (HNR). The Southwest region had a slightly greater percentage of the variation attributable to environment with the Mid-South having less than the average. These slight regional differences suggest either more variation in the weather, field growing conditions, and/or consistency of management in the Southwest with less variation in the Mid-South. Differences were minor and did not alter the conclusion that where and how the crop is grown is a larger contributor to earliness than variety.