National Emergency, Not
There is no national emergency at the southern U.S. border.
The conditions there have not substantially changed today, or within the past 24 hours, or within the past week, or within the past month, or within any reasonable time frame looking back. As the popular cliché goes, and it applies here: "it is what it is." Nothing has changed. The idea that there's an emergency is an insult to the American people's intelligence.
The reality? Trump made a promise that he couldn't follow through on. Eat your mistake, Trump, whether you like it or not.
Yes, there should be improved technology at the border. Yes, there should be more CBP agents at the border. The idea of these two points is that better, real-time detection of migrants crossing at the border ideally should help to minimize migrants putting themselves in dangerous, inhospitable conditions that may put their health and lives at risk. Walls don't do that, and for that reason alone it's inhumane.
And yes, in the bigger picture, the immigration laws and overall immigration system deserve a long hard analysis and an objective overhaul. But of course a wall does nothing to address the underlying challenges and deficiencies of the current system. Actual leaders -- with the input of various cross-disciplinary experts, relying on research and statistics -- would be required for that large a task. False leaders, on the other hand, sadly rely on PR gimmicks and populist slogans like a band-aid for a broken bone.