Supima is the marketing brand for American-grown Pima cotton. This type of cotton is of exceptional quality and softness thanks to its fibers which are 30% longer than average. This type of cotton is therefore softer and 45% stronger than normal cotton. Being grown exclusively in Texas and California, only 1% of apparel worldwide is made with Supima Cotton. Because Pima cotton is so much softer, it is very popular for textiles like t-shirts, socks and underwear.