Beginning in 1999 and projected to last through 2008, all quarter dollars coined by the United States Mint will feature reverse designs commemorating each of the 50 states. These are to appear every ten weeks or so, for a total of five issues per year, and the states are to be honored in the order in which they were admitted to the Union. The obverse of the existing Washington Quarter has been modified to accommodate the statutory inscriptions relocated from the reverse. This series is being widely collected by both established coin enthusiasts and the general public. As of this writing, only two significant varieties exist for this series, the 2004-D Wisconsin quarters with extra leaf high and with extra leaf low.