When people study history one or two hundred years from now. They will remember this era for two things: positively, because we began to explore space and negatively because we opposed most migration. Today we look at the idea of slavery as an abomination but in 1830 slavery was common and support for abolition was rare. The same is true for free migration. Today everybody sees a reason why we can’t allow free migration so they are opposed to even moving in that direction. History may see us the way we look at slaveholders.
Ethics change don’t get on the wrong side if you want to be remembered well by history.