Louisiana Purchase?

The Louisiana Purchase was the acquisition by the United States of more than 530,000,000 acres (828,000 mi² or 2,100,000 km²) of territory from France in 1803, at the cost of about 3 cents per acre (7¢ per hectare); US$15 million or 80 million francs in total. Plus interest, America paid a total of $27,267,622 in exchange for the Louisiana territory. (If adjusted for the relative share of GDP, this amount would equal approximately $707.6 billion in 2005, or about $1,800 per hectare.)