If Elon Musk’s Boring Company succeeds, the fantasy of slipping into a pod and being whisked from Washington, D.C. to New York City in less than 30 minutes may become a reality. As startling as that might be, such transformational projects are nothing new. Think of how Americans of a half-century ago felt once the national interstate highway system was complete and a cross-country road trip shortened from two weeks to five days. Infrastructure improvements in the U.S. – such as the interstate system, built in the 1950s and 1960s, the first transcontinental railway in the 1860s, and the Erie...