What was the last year US 20 dollar gold pieces were minted?

1932 was the last year that US $20 gold coins (a/k/a "double eagles") were minted for circulation. Many were melted so today they're very rare, with retail prices of at least $10,000 as of 07/2013.

445,500 double eagles were minted in 1933 but the US went off the gold standard before any could be put in circulation. All but a few 1933 double eagles were melted.

A dozen or so 1933 double eagles were held back when the order to melt was given. One is preserved in the Smithsonian Institute in Washington, DC; see the link below. At the time another one was sold to Egypt's King Farouk. It was eventually seized by the US Secret Service but was released when a court ruled against the government's seizure. It re-sold for about $8 million in 2002. The remainder were secretly held by the family of a Philadelphia coin dealer until the second decade of the 21st century. The legality of their ownership is under debate at this writing; it's unlikely the family will be able to keep them.