EL PASO, Texas People walking over the Paso del Norte Bridge linking this West Texas border city to Mexico can watch President Donald Trump’s border wall getting bigger in real time. Workers in fluorescent smocks can be seen digging trenches, pouring concrete and erecting rust-colored slabs of 18-foot-high metal to replace layers of barbed wire-topped fencing along the mud-colored Rio Grande, which is usually little more than a trickle. Most of the more than 70,000 people who legally cross four city bridges daily — to shop, go to school and work — pay the construction in the heart of downtown...