What is the main idea of the poem complaint of el rio grande

The main idea presented in the poem "Complaint of El Rio Grande" is the socio-political issue of immigration and the building of a border between Mexico and the US, separated by the river Rio Grande.

Explanation:

"Complaint of El Rio Grande" is a poem written by Richard Blanco. The poem is personified by the river El Rio Grande, complaining about the political issue of building a border between Mexico and the US. The river recognizing its role in nature complaints that it was meant to serve all and not selected few, not to divide, not to murder, or drown anyone. The poem also reveals the connotative meaning that how the river also serves as a border between the two nations.