One major problem the United States was suffering with when John F. Kennedy became president was HIGH UNEMPLOYMENT RATE.
The terrible sewer and water system that was infecting countless people by diseases like typhoid. <span />
World War I, which lasted through Jul 28, 1914 to Nov 11, 1918.
https://www.history.com/topics/world-war-i/world-war-i-history
Info at the link
A primary source is from someone who was apart of the event that’s being sourced, such as a holocaust survivor recounting the events of the holocaust, or someone who witnessed a murder. A secondary source would be someone sharing the primary source, such as a newspaper or a book! Hope this helps!