“The United States is not so strong, the final triumph of the democratic ideal is not so inevitable that we can ignore what the world thinks of us or our record.” ~ Committee on Civil Rights, appointed by President Truman
Given the grumblings of unrest in the 1940s (which ended up exploding in the 1960s), Truman appointed a committee to investigate civil rights and to suggest ways to strengthen them.
Against the backdrop of the Cold War, the Committee underscored the need to show democracy as the legitimate victor to Communism; democracy as practiced in the US has to divest itself of the racism that pervaded the US. Only by being a champion for civil rights could the US model democracy for the rest of the world.
Unfortunately, over the centuries, the US has failed to live up to its principles, demanding civil and human rights elsewhere but allowing an under-privileged class to flourish in its borders.
Is an underclass necessary for a democracy to exist? We saw it in ancient Greece. We see it in the US (in the past and today).
The common wisdom is that Communism failed and democracy (or capitalism, since democracy and capitalism are intertwined in the US) won. But won is a strange term, implying that we all share in the victory.