Due to its indeterminate growth habit, maturation of cotton (Gossypium hirsutum L.) is affected by many environmental and cultural factors. An easy and reliable measure of its progression toward maturity that can be attained during crop development is needed for both production and research programs. As a cotton plant develops, first-position flowers progress toward the plant apex, and their relative position can be determined by counting the number of main-stem nodes above the uppermost white flower. After plants attain nodes above white flower = 5.0 (physiological cutout date; i.e., flowering date of the last effective boll population), subsequent flowers have a low probability of producing bolls of adequate size and quality. The objective of this study was to evaluate physiological cutout date (days from planting to physiological cutout) as a measure of maturity in cotton by comparing it with two established harvest-based methods: mean maturity date and percentage of crop harvested in the first of two harvests (% first pick). Comparisons were made in three tests: (i) evaluation of varying treatments for thrips (Frankliniella spp.), (ii) nitrogen rate on three cultivars, (iii) cultivar evaluation at different locations in Arkansas. Within each test, sequential nodes above white flower counts were used to determine physiological cutout date, while mean maturity date (days from planting until 50% yield can be harvested), and % first pick were determined from sequential harvests. Significant variation was found within each test for all of the maturity measurements. Physiological cutout date tended to be closely related to mean maturity date and % first pick. Exceptions occurred when values of % first pick exceeded 90% (variation in maturity was not expressed) and when Verticillium wilt (caused by Verticillium dahliae Kleb.) affected crop maturity after physiological cutout. Thus, physiological cutout date provides a precise, easy, and reliable measurement of the accumulated effects of environmental and cultural factors on crop development that occurs before the flowering of the last effective boll population.