How did JFK know Lyndon B. Johnson?

John F. Kennedy and Lyndon B. Johnson first became acquainted in the early 1940s when both were serving in the U.S. Congress. Their political paths crossed as they worked on various legislative initiatives, and their relationship deepened during the 1960 presidential campaign, when Johnson was chosen as Kennedy's running mate. This partnership was instrumental in helping JFK secure the presidency, as Johnson's Southern roots and political experience appealed to a broader electorate. Their collaboration continued during Kennedy's presidency until his assassination in 1963, after which Johnson succeeded him.