There are so many things to say. For the sake of space, I will limit my answers to three important points.
First, the war provided a great impetus among Black American, as many fought in the war and they will able to break the cycle of poverty. Over a million black soldiers fought in the war. After the war, there was a new sense of pride and power. For instance, there was a surge in registered black voters and great luminaries like Thurgood Marshall even argued before the supreme court. Here is another example. On December 5, 1946 President Truman created a committee on Civil Rights. In short, minorities became more politically powerful.
Second, from another perspective, many new immigrant moved to America. For example, in 1965 the quota act was repealed, which allow for an influx of Asians to come to America. So, we can say immigrants have become more numerous. Moreover, they have been able to create ethnic enclaves.
Finally, minorities have gained more power in our society. We see this from even the top in Barack Obama. We also see this in the media as well. In a word, we are seeing more minorites in positions of power.