How did the United States support the Allies with economic aid while staying out of the fighting during WWII?

The United States were officially neutral until the bombing of Pearl Harbor, Hawaii on December 7, 1941, but assisted in many other ways due to fear of a WWI repeat.

To begin, in 1939 the United States implemented the Cash and Carry policy of the Neutrality Acts that allowed the Allies (Great Britain and France) to buy arms and other goods from the United States so long as they paid in full and transported their purchased goods with their own ships.

Then, in March of 1941, the United States implemented the Lend-Lease Act which allowed the US to sell, lend or lease any military equipment or arms to Allies in WW2. This was a desperate attempt at maintaining neutrality because the Allies were too poor to pay in full up front for the things they needed and didn't have the spare resources to transport them, so the US compromised and helped them out.

Another thing that the US did to help the Allies was not offer the same assistance they were giving the Allies to the Axis powers. The US also basically agreed with the British and French blockade of Germany that prevented trade between Germany and the US, simply not doing anything to assist Germany assisted the Allies.