Langston Hughes uses the symbol of rivers often in his poetry. In "The Negro Speaks of Rivers" Hughes writes about the rivers Black people have known throughout history. He then compares his soul to a river. Just as this river is old, deep and flowing so is the Black soul.
The river is often used in Black American spirituals as a sign of freedom. To pass through the river to freedom, to be carried by the river to freedom etc.
In Hughes' poem "Suicide's Note," he writes:
The calm,
Cool face of the river
Asked me for a kiss.
Here we see the river providing freedom in different a way. Through the taking of ones life. It is a very dark poem, that has little hope in comparison to songs like "Deep River and poems like "The Negro Speaks of Rivers," while the speaker finds freedom, it's because they could no longer persevere.