The Act established extensive federal oversight of elections administration, providing that states with a history of discriminatory voting practices (so-called "covered jurisdictions") could not implement any change affecting voting without first obtaining the approval of the Department of Justice, a process known as preclearance
. These enforcement provisions applied to states and political subdivisions (mostly in the South) that had used a "device" to limit voting and in which less than 50 percent of the population was registered to vote in 1964
. The Act has been renewed and amended by Congress four times, the most recent being a 25-year extension signed into law by President George W. Bush in 2006.