I believe it meant the institution of slavery.
Should you mean the spread of more African-Americans. It is my feeling, that not many whites (except those who wanted to work blacks ) wanted blacks around. America and the world itself was very racially conscious. The advantage of a multi-cultural society is debated even today. Let me pose you this question. In the Federalist Papers, Mr. John Jay had this to say:
With equal pleasure I have as often taken notice that Providence has been pleased to give this one connected country to one united people--a people descended from the same ancestors, speaking the same language, professing the same religion, attached to the same principles of government, very similar in their manners and customs, and who, by their joint counsels, arms, and efforts, fighting side by side throughout a long and bloody war, have nobly established general liberty and independence.
My question is this. Reading this, do you feel the founders thought that, if not of British ancestry, at least those of a white Judeo-Christian background were the only ones entitled to be citizens or whether all men of whatever race, religion and creed should be entitled to the same representation under law? Is America a result of the Enlightenment or is it a continuation of the charter rights of Englishmen so to speak?