I prefer a wall built around all the big "liberal" cities that want to be illegal drug havens and sanctuary cities.  Let them go ahead and do that,  then after all the riff raff has migrated just 'wall' them all in.  They can inject, smoke, snort or huff anything they want and tax  each other at a 100% rate. We can have places of entry for 'legitimate' business, the rest can stay behind the wall and away from the rest of us.  Great idea.  I love it!