As a Christian name, Ruth has been in use since the Protestant Reformation. In England it was associated with the archaic word ruth meaning "pity, compassion" (now only commonly seen in the word ruthless). The name became very popular in America following the birth of "Baby" Ruth Cleveland (1891-1904), the daughter of President Grover Cleveland.
In the United States this form was more popular than the full form Elizabeth from 1958 to 1978, and was in fact the top ranked American name between 1962 and 1969.
American writers Jack London (1876-1916) and Jack Kerouac (1922-1969) were two famous bearers of this name. It is also borne by the actor Jack Nicholson (1937-) and the golfer Jack Nicklaus (1940-). Apart from Nicklaus, none of these famous bearers were given the name Jack at birth.
In the United Kingdom this form has been bestowed more frequently than John since the 1990s, being the most popular name for boys from 1996 to 2008.
As an English name, Hannah was not regularly used until after the Protestant Reformation, unlike the vernacular forms Anne and Ann and the Latin form Anna, which were used from the late Middle Ages. In the last half of the 20th century Hannah surged in popularity and neared the top of the name rankings for both the United States and the United Kingdom.