Short answers, pulled from the story.
Franklin D. Roosevelt entered the White House in 1933 as the nation faced the economic calamity of the Great Depression. His New Deal offered a radical shift from previous laissez-faire approaches to government intervention in the economy.
President Lyndon B. Johnson signed legislation creating Medicare and expanding welfare programs funded by massive public expenditure in 1964. This action aligned with modern liberals embracing Keynesian theory which argues that government management can keep unemployment low while maintaining inflation control.
The Civil Rights Act of 1964 permanently ended legal segregation across the United States after decades of resistance. Martin Luther King Jr.'s I Have a Dream speech during the March on Washington in August 1963 galvanized national support for voting rights leading to this outcome.
Richard Nixon won the presidency in 1968 as Republicans capitalized on Southern white backlash against integration. By 1968, conservative Democrats began an exodus from the party following the passage of civil rights legislation which transformed American politics into a polarized system.
Forty-nine percent of self-identified liberals held college degrees compared to twenty-seven percent nationally according to the 2005 Pew Research Center study. Household incomes exceeding seventy-five thousand dollars applied to forty-one percent of liberals versus twenty-eight percent overall.