Traditionally, Madison was a surname, meaning son of Maud.
Recently Madison has become a very popular female given name in the United States. There is a curious story behind this popularity: According to the Social Security Administration's statistics, from a practically non-existent girl's name before 1985, Madison rose to being the second most popular name given to female babies in 2002. A possible reason for this phenomenal rise in popularity is the 1984 movie Splash, where Daryl Hannah played a mermaid who adopted the name 'Madison' after seeing a Madison Avenue street sign. When the selection is made, Tom Hanks' character says "but Madison isn't a name!"
Madison is also used, to a lesser extent, as a male given name. According to the Social Security Administration, Madison can be found within the top 1,000 names for boys up until about 1952. It returned to the top 1,000 ranked boy's names in 1987, but remains one of the lowest ranking boy's names in the U.S.