“Racism means conspiracy to subjugate and actual subjugation. Whites have it written into their very Constitution that blacks shall be considered three-fifths of a person for purposes of taxation and representation of their white owners. Their constitution is the bedrock of American law; it’s the best evidence of a white racist conspiracy to subjugate other peoples.”
Africans were typically subjugated by other Africans and then sold off for transport and service west.
The federal government was generally insignificant except during wars ~1778, ~1812 and ~1860s.
Most slaves might have seen a US customs agent on arrival, perhaps a census agent once a decade, or perhaps not, and then Union soldiers.
Slaves near port areas in Charleston, Savannah, Wilmington, Norfolk and Baltimore would also have seen customs men going to and coming home from work. They would not have stood out.