Just how much is $700,000,000,000?

$700,000,000,000 is more than virtually any other US government endeavor dating back to the Louisiana Purchase. Adjusted for inflation, only one of the following cost more. Can you guess which one it is?

1. Hoover Dam
2. Panama Canal
3. Gulf War I
   
4. The Marshall Plan
5. Louisiana Purchase
6. Race to the Moon
7. Savings & Loan Crisis
8. Korean War
9. The New Deal
10. Gulf War II / War on Terror
11. Viet Nam War
12. NASA (50-year cumulative spending)
13. World War II
    

Watch this Big Budget Events slideshow for the answer.