South Carolina led the southern walk-out from the 1948 Democratic National Convention. - Eric Foner

The collapse of communism as an ideology and of the Soviet Union as a world power has made possible an unprecedented internationalization of current American values, among them free choice in the consumer marketplace, reduced government economic regulation and an emphasis on individual self-fulfillment rather than the social good, all promoted by an internationalized mass media and consumer culture.

Andrew Johnson lacked Lincoln's qualities of greatness. While Lincoln had been open-minded, willing to listen to criticism, attuned to the currents of northern public opinion, and able to get along with all elements of his party, Johnson was stubborn, deeply racist, and insensitive to the opinions of others. If anyone was responsible for the wreck of his presidency, it was Johnson himself, first by establishing new governments in the South in which blacks had no voice whatsoever, and then refusing, when these governments sought to reduce freedpeople to a situation akin to slavery through the Black Codes, to heed the rising tide of northern concern. As congressional opposition mounted, Johnson refused to budge.

Even as the United States has risen to become the predominant international power, however, conflict has persisted over the nature of American society itself and what its role in the world should be.