Margaret, you have several great responses here. I'd like to add that the US Civil War, fought as a dispute between slaveholding southern states and "free" northern states, ended slavery by law in the US in 1865. Northern states abolished slavery before this, albeit at different times. For example, Massachusetts began its gradual abolition process in 1783. In Pennsylvania and neighboring New Jersey, slavery was prominent into the 1840s. And in neighboring Maryland, where Baltimore is, slavery persisted through 1864 despite Maryland aligning with the northern side of the Civil War.
Also, keep in mind unscrupulous white criminals would kidnap free northern Black folks and sell them into slavery in places like New Orleans. This is one reason it would be important to document one's status as a "free person of colo(u)r."
Another thing to keep in mind: in one of those documents Benjamin Gale is listed "coloured," but that is crossed out and he is listed as "mulatto," an archaic and offensive term for mixed-race people. In the American South, this usually indicated European and African heritage. In the New England region of the US, especially in the eighteenth century, it often indicated mixed African and Indigenous American heritage. I think it's a long shot, but it's worth keeping an open mind that the "free person of color" Benjamin Gale may have Native American heritage.