This statement is most closely associated with Voltaire, a prominent Enlightenment philosopher who advocated for freedom of speech and tolerance. He believed in the importance of allowing differing opinions to be expressed, even if he did not agree with them personally.
Prior to the attack the United States was still (officially) neutral in the war. The attack of Pearl Harbor guaranteed that America would immediately enter the war on the Allied side.
At this time in American history people viewed themselves as from being a particular area or colony rather than as a part of a country as a whole. Stating this meant he saw himself as an American rather than just from Virginia.
In this line, Hughes is asserting his own identity as an African American person and expressing his right to celebrate and claim ownership of America, just like any other citizen. He is asserting his perspective and presence in a country that has not always fully embraced or acknowledged the contributions of African Americans.