Thirty-six American cottons of many genotypes were grown by W.R.Meredith at Stoneville, MS in 1995. Fiber Properties were measured byMicronaire, Areolometer, HVI, AFIS, and the 50% X-ray Intensity Angleof the 002 diffraction arc of bundles of cotton fibers. Fiber bundle tenacitywas measured by HVI and fiber bundle tenacity and elongation weremeasured by Stelometer. The 50% X-ray angle was the key fibermeasurement for evaluating all other fiber properties. Simple correlationanalysis shows that as the 50% X-ray Angle decreases fiber strength andlength increase; fiber tensile strain, perimeter, linear density, and fibermaturity ratio decrease. Best results (highest correlations) are obtainedwhen Stelometer bundle modulus is used rather than just Stelometertenacity or HVI tenacity. Thus, Secant Modulus is a more comprehensivemeasurement of fiber bundle strength than tenacity. When multiplecorrelation evaluations are made to compare each of the several bundlestrength parameters with the 50% X-ray angle and all fiber properties, X-ray angle and all fiber properties except one fiber property - AFIS perimeter- are excluded. The reason for this is statistical col linearity among all of thefiber properties. Thus, the 50% X-ray Angle, though an important measure of fiber properties and strength, can be supplanted by the measurement ofAFIS perimeter.