Mexico border sealed?

Ok, before you read this question... Remember it's just that. It has not happened nor am I implying that it will happen anytime soon... So if don't give me a bunch of reasons on why it won't happen...just what it would mean.

If due to a national emergency, the border was sealed, guarded, etc... what do you believe that, that would have upon our politics, society, etc... With the intense fighting between drug cartels and Mexican military or other drug cartels and now a disease the WHO (not the band) called "a public health emergency or international concern" this could legitimately happen. It has just as great of a chance of not happening....but I'm not asking about that...