Answer:
The presidency of Lyndon Johnson changed the political paradigm of the United States of America. Historically, the Republican Party was representative of the north of the country, and advocated the rights of the minorities of American population (African-Americans, immigrants, poor, among others); while the Democratic Party used to represent the interests of the south of the country, and specifically the white population.
The presidency of Lyndon Johnson confirmed what Franklin D. Roosevelt and John Fitzgerald Kennedy had begun: a political inversion between these political parties, in which the Democratic Party and the Republican Party practically exchanged their ideals and their areas of influence. Thus, the Democratic Party began to defend social rights, while the Republican Party became socially conservative.
For example, today in the Democratic Party we find favorable positions for immigrants, while in the Republican Party the vast majority of its members are against immigration.