Donald Trump wants to build a wall on our southern border. Good luck with that. Walls generally are unsuccessful; however Republican walls around inner cities have been remarkably successful.
The poor and minorities are kept in inner city poverty by invisible walls constructed by the prejudices of white suburban Republicans. You can’t see the walls, but they exist in the minds of the poor and oppressed as well as in the minds of the oppressors. The poor and minorities are herded together in cramped and decaying neighborhoods where they can more easily be monitored.
Please see Great Wall of China