The line of latitude at 23.5 degrees North is called the Tropic of Cancer. Its geographical significance lies in the fact that it marks the northernmost boundary of the tropics and the most northern point at which the sun's rays can be directly overhead at noon.
The Tropic of Cancer passes through Hawaii, Mexico, the Bahamas, northern Africa in the Sahara Desert, parts of the Middle East and southern parts of Asia. Its counterpart, the Tropic of Capricorn, is 23.5 degrees South latitude. The Tropic of Capricorn is the southern boundary of the tropics and runs through Australia, southern Africa and South America.