Jeff Thom, age 9, of Eugene, Oregon, for his question:

How long did it take to carve Mount Rushmore?

You would expect it to take a long time to finish the largest stone carving in the world. The actual job of carving the four giant heads on Mount Rushmore lasted through more than 14 years. But the work really began before this. The sculptor was Gutzon Borglum, who was famous for creating giant sized statues. He spent several years designing the Mount Rushmore heady and planning how the enormous job could be done. In 1927, the actual carving work began on the steep granite mountain in South Dakota.

Teams of workmen dynamited and drilled while the artist showed them how to copy his models. His son Lincoln worked with him and understood the plans. Several times the work was interrupted, but gradually the great heads took shape. In 1941, after 14 years, they were almost finished    and Gutzon Borglum died. The last few details were finished by his son. At last the world's biggest stone carving was unveiled and Mount Rushmore became a National Memorial.