And you would rather see Americans killed by (1) illegal drugs, (2) gangsters, and (3) criminals pouring through the borders? I don't think anyone has a real handle on the numbers involved, but it could well be in the hundreds of thousands.
Actually industries in the USA would thrive if all products from Mexico were barred altogether. This would mean that manufacturing plants and factories would have to be set up on US soil to hire US citizens, who would then earn an honest and good income. Jobs were shipped to Mexico to undermine American jobs and create more unemployment, homelessness, and crime. That should never have happened.
With a sealed border, the cartels would not be receiving millions (or billions) daily from the USA for all those drugs they have been shipping daily. At the same time, when the Mexican government realizes that the wealth from America is not flowing southward, they would be compelled to do something serious about the whole ugly scenario in Mexico. Those governments have been corrupted by the drug lords, only because the drug lords have extracted billions from Americans. When that cash flow begins to disappear, there could be a huge change in the way Mexico operates.
The real issue is having the guts to do something meaningful, instead of simply talking and threatening. Even the border states did not have to wait for federal action. Had they chosen to act and shut down illicit traffic through their sovereign territories, the Feds would have had to wake up and deal with the issue. Everyone has complained about a porous border, illegal immigrants, illegal drugs, gangsters, criminals, coyotes, etc. but no one has take serious action.
The other closely related issue is the existence of at least 20 million illegals in America right now. That has a huge impact on (a) the economy, (b) elections, (c) crime, (d) disease, and (f) cultural impact. Immigration laws have been flouted, which means that the rule of law has been destroyed, and a lawless country has been created just like that. Now those 20 million are going to increase by a few more million, and pretty soon America will become another third world country like Nicaragua or Guatemala. Is that what you wish to see? And that does not even address the entry of Islamist and other terrorists through the porous southern border,