The poem "As I Grew Older" is about the poet's dream which he compares to the sun (the rising wall), and about the obstacles he tackled on his way to achieve it. Since the speaker is a dark African-American poet, we naturally think that the wall on his way is racism. However, the poet hasn't mentioned that specifically and made the meaning of the wall, and the meaning of the poem unclear. In my opinion, "As I Grew Older" is a lot about racism, but not only.
In the poem the speaker mentions the fact that he is a black man ("I am black", "My dark hands!"). The purpose of this repetition is to make the reader understand that in his life, the wall symbolizes racism. However, the poet hasn't mentioned that specifically, on purpose to let the reader decide what the wall symbolizes for him. The poet wants us to understand that he had suffered from racism. In that way he also criticizes the society. He wants to say that although his skin color made it harder, he fought to make his dream come true, and if he fought against his tough racist wall, anyone can do this with less thick walls.
The message of the poem is: don’t be afraid to break the walls in your life, which prevent you from achieving your dream. Those walls exist in everyone's life, which means there are many kinds of walls. Those walls, for example, can be discrimination against women or older people, preventing them from getting a job. Other walls might be an economic problem preventing children from having a successful future. I think that the toughest wall is unsupportive families, preventing their members from achieving their dreams.
In conclusion, in his poem Langston Hughes shows us that in his life he fought against racism, which constituted the obstacles in his life. However, he is still giving us the option to choose what the wall means for us: discrimination, economic difficulty or unsupportive family.