>your country is 40% nonwhite
I guess you're reffering to the US which is not my country but fair enough let us explore the idea of a wall and why it is a good thing.
1. It keeps out welfare niggers
2. It keeps out degenerates and yes I don't like them
3. It should keep out jews and their non government leftist organizations who push for abortion and wimminz rights. 
4. It keeps drug cartel spics and niggers from jumping over a fence to enter the country. 
5. The great wall of china. The best nigger repellent ever created by man.