<P> Construction began on October 4, 1927 . In 1935 Borglum appointed Italian immigrant Luigi Del Bianco as chief carver . </P> <P> George Washington's head was started first . Due to the economic instability of the United States caused by the Great Depression, it was completed in seven years, and dedicated to the public on Independence Day 1934 . A large American flag was placed over Washington's head before it was revealed, and this became a tradition for each of the presidents' heads . </P> <P> Thomas Jefferson's head was started next, to the right of Washington . Before the head was complete, Borglum requested that it should be blasted off due to poor rock quality . Jefferson's head was restarted on Washington's left . Jefferson's head was dedicated in 1936 . </P> <P> Abraham Lincoln's head was the most challenging because of his beard, but his head was completed on the far right of the cliff . Lincoln's face was finally dedicated on September 17, 1937, which was the 150th anniversary of the signing of the Constitution of the United States in 1787 . </P>

Who built mount rushmore and how long did it take