The government's financial bailout will be the most expensive single expenditure in American history, potentially costing around $7.5 trillion -- or half the value of all the goods and services produced in the United States last year. In comparison, the total U.S. cost of World War II adjusted for inflation was $3.6 trillion. The bailout will cost more than the total combined costs in today's dollars of the Marshall Plan, the Louisiana Purchase, the Korean War, the Vietnam War and the entire historical budget of NASA, including the moon landing, according to data compiled by Bianco Research. It remains to be seen whether the government's multipronged approach to bail out banks, stimulate spending and buy up mortgages will revive the economy, but as the tab continues to grow so does concern over where the government will find the money. Monday the government guaranteed an additional $306 billion to bail out Citigroup, and today Treasury Secretary Henry Paulson pledged $800 billion to make credit more available to consumers and small businesses, and to buy up mortgages from Fannie Mae and Freddie Mac. Congress last month allocated $700 billion for an emergency bailout of some of Wall Street's most storied firms by purchasing their troubled assets. The funds allocated through the Troubled Assets Relief Program are but a small part of the government's overall bailout spending. Bailout programs also include a Federal Reserve plan to buy as much as $2.4 trillion in short-term notes called commercial paper that began Oct. 27, and an FDIC plan to spend $1.4 trillion to guarantee bank-to-bank loans that commenced Oct. 14, according to Bloomberg News, which first compiled the total cost of the bailout.