Card dusts collected from cotton grown in California, Texas, and Mississippi, and processed at the Cotton Quality Research Station, USDA, Clemson, SC, were chemically characterized by proximate analyses and energy-dispersived X-ray fluorescence studies. Elemental contents of cardroom dusts successfully differentiated the dusts according to growing areas of cotton used to generate the dust samples. Variations in ash contents of the dust samples are highly correlated with variations in silicon, iron, and aluminum contents indicating soil contamination. The California cardroom dusts have high levels of cellulose relative to the Texas and Mississippi dusts.