President Donald Trump has built another wall, and he thinks everyone else is going to pay for it. But his decision to impose sweeping tariffs of at least 10% on almost every product that enters the US is essentially a wall designed to keep work and jobs within it, rather than immigrants out. The height of this wall needs to be put in historical context. It takes the US back a century in terms of protectionism. It catapults the US way above the G7 and G20 nations into levels of customs revenue, associated with Senegal, Mongolia and Kyrgyzstan. What occurred...