Describe the three most severe downturns in the united states economy since the 1920s by completing the timeline

three most severe downturns in the United States economy since the 1920s  were: 
- The depression of 1921, happened because we receive a blowback for all the money we spent on world war I
- The Great Depression of 1929-1933 , happened because our investment to expand our business to all over the world
- The Great Recession of 2007, happen because of the mortgage crisis, causing Global financial crisis