This was a result of a Republican amendment to the Clinton-administration increase in the federal minimum wage (around 1992 - 1995. Subtitled "A bill to increase the take-home pay of workers..." or something like that, if I recall correctly. It should be available at
http://thomas.loc.gov but the site isn't terribly easy to search.). Another Republican amendment to the same bill decreased the minimum wage for workers who receive tips to $2.XX (I can't remember exactly.)