American Mensa
With more than 50,000 members, American Mensa is the largest national Mensa operating under the auspices of Mensa International, Ltd. There are currently more than 130,000 members worldwide, and an estimated six million Americans are eligible for Mensa membership. Mensa members range in age from 2 to 106. They include engineers, homemakers, teachers, actors, athletes, students, and CEOs, and they share only one trait — high intelligence.