Despite the apparent responsiveness of the executive branch, racial tensions did not abate during the war. Race riots erupted in northern cities like Detroit and New York, exposing tensions that continued to plague the entire country. As the riots made clear, injustice was not confined to the American South; blacks in every region were more determined than ever to gain their rights as citizens in a democracy. The wartime cry among blacks was encapsulated in the notion of the Double-V, which asserted that it was essential to achieve victory not only against dictators abroad but also against the tyranny of racism at home.
Indeed, the war strengthened the determination of the African American population to claim their rights as American citizens. The United States and its allies had assumed the burden of sweeping the racist ideologies of Nazi Germany and Imperial Japan from the world scene. With the successful conclusion of the global conflagration, the notion of state-sanctioned racial, ethnic, or religious persecution lost legitimacy throughout the world. And that in turn undermined such thinking in the United States. If it had been worth fighting to stamp out racial persecution in Europe and Asia, then it was surely reasonable to stamp out racial persecution in Alabama. This argument, which had been made throughout the war, came to have considerable power once peace was achieved.
Another significant implication of the war was the movement of blacks from the rural South to the urban North. Due to increasing economic opportunities in the North and the mechanization of southern agriculture (especially in the harvesting of cotton, which decreased the demand for black labor), some 700,000 blacks headed north during the war years. Nor did this northward migration end once the war was over. In fact, during the 1940s as a whole, over a million blacks left the region, while in the 1950s, more than 1.5 million blacks moved north, abandoning their rural roots for cities from New York to California. As the historian Harvard Sitkoff has noted, this mass migration "fundamentally altered the configuration of the race problem." And over time, it would transform social, cultural, and political life in postwar America, affecting everything from presidential politics to popular music.
In the postwar political realm, Harry Truman built on the actions of his predecessor, issuing an executive order in 1948 that ended segregation in the military. This was a significant milestone, though it would be some time before the armed forces fully implemented the President's directive. During the first months of 1948, Truman also spoke out forcefully on behalf of civil rights reform. When the Democrats assembled for their convention in the summer of 1948, northern Democrats such as Minneapolis mayor Hubert Humphrey pushed for a strong civil rights plank in the party platform. This led to a rupture in the Democratic Party during the presidential campaign. Led by Strom Thurmond of South Carolina, some southern Democrats refused to endorse Truman and formed a States' Rights party that was dedicated to preventing any supporter of federal civil rights reform from reaching the White House. That fall, Thurmond captured four southern states. Though Truman won the White House, the lesson was clear: the civil rights struggle had the potential to break up the Democratic Party.