How does this song relate to slavery in the united states?
ye spirits of the free,
can ye forever see
your brother man
a yoked and scourged slave,
chains dragging to his grave
and raise no hand to save?
say it you can
- from a collection compiled by william wells brown,1848

This song relates to slavery in the United States because it questions how white people can see the suffering of slaves and do nothing

Explanation:

The music implies that whites and blacks are brothers, belong to the same species and are human beings capable of feeling the same feelings and sensations. For this reason, the music questions how the spirit of the free (the spirit of the white people) can live in peace, seeing their slave brothers living in misery and violence and doing nothing to help and free these people.

b)

it created free trade throughout the colonial territories.