How did the US government raise money for World War 1?

The US government raised money for the war effort by means of:

1) At first by taxation - which was only sufficient to pay for normal expenditure;

2) the second measure was that to float a public loan by issuing interest-bearing bonds, which were sold at below face value, in order to offer an attractive rate of interest. Though successful it was insufficient to solve the problem of liquidity;

2) Then , to sort out the problem, by the issue of paper money, authorized by Congress in February 1862. At the end of the war there were in circulation $ 431 million of notes, called Greenbacks because of their color.