Originally, the key was narrower than it is today and had the shape of a keyhole, measuring six feet (1.8 m) wide, hence "the key", with the free circle as the head, and the shaded lane as the body. Due to the narrowness of the key, imposing centers, such as George Mikan, dominated the paint, scoring at will. To counter this, the key was widened into 12 feet (3.7 m) from 6 feet (1.8 m) at the onset of the 1951–52 NBA season.[5]
Men's professional basketball in the United States (notably the National Basketball Association) widened it further to 16 feet (4.9 m) on the 1964–65 NBA season to lessen the effectiveness of centers, especially Wilt Chamberlain.[6] The NCAA retains the old 12 feet key to this day.
On April 25, 2008, the FIBA Central Board approved rule changes that included the changes in the shape of the key; the key is now rectangular and has virtually the dimensions as the key used in the NBA. In addition, the no-charge semicircles or the restricted area arc is also created.[7]