1/4 Dollar 'Washington Quarter' South Dakota - Silver Proof

The 50 State Quarters program, authorized by Congress in 1997, ran one new reverse design every ten weeks from 1999 through 2008. South Dakota's 2006 entry was the 40th issue in the sequence. San Francisco struck the silver proof versions exclusively, as it had for the entire program, having shed most of its circulating coinage responsibilities decades earlier to focus on collector issues.

Mount Rushmore's sculpting was funded partly through federal appropriations lobbied by South Dakota's congressional delegation and took fourteen years to complete, finishing in 1941 — the same year Gutzon Borglum died, leaving his son Lincoln to oversee the final blasting.