How many african americans served in the us navy during the civil war?

I believe it was approx 20,000 African Americans.

By the end of the Civil War, roughly 179,000 black men (10% of the Union Army) served as soldiers in the U.S. Army and another 19,000 served in the Navy

the answer to your question is a. the salt plains

in 1811, he led an expedition, known as the george c. sibley expedition, to improve relations with the pawnee and kansa tribes, and also to locate the rumored jefferson's salt mountain

because it !