Dan (rank) highest level that might be attained, with instructor certification and judge/judgment authorization being understood as higher-level or more sophisticated. Many arts use between one and ten dan ranks: In some martial arts, black belts are worn for all "dan" grades. In others, the highest grade (10th "dan") wears a red colored belt. In Jūdo and Shotokan 6th to 8th "dan" may wear a red and white-patterned belt and 9th to 10th "dan" may wear a solid red belt. There is some variation even within styles. Generally, belts do not have markings that indicate the actual "dan" grade. Okinawan styles used
Judo in the United States AAU sport, and there have been national competitions and tournaments ever since. The United States formed an Olympic team and competed in the 1964 Summer Olympics, which it continues to do to this day. Judo is now practiced by and estimated 100,000 American men, women, and children (25,000 registered in either the USJA, USJF, and USA Judo). America's first major contact exposure to judo came through President Ulysses S. Grant in 1879. He was in Japan for a state visit and observed a judo demonstration. In 1889, Kanō Jigorō gave a lecture on the philosophy of judo to several Americans;