In April 2020, the venture capitalist Marc Andreessen published a widely read essay titled “It’s Time to Build.” For all its supposed dynamism, the U.S. economy appeared slow and inflexible in the face of a once-in-a-generation crisis. Masks and ventilators were in short supply, but this inability to rapidly adjust wasn’t specific to Covid-19: America had long struggled to build housing, high-speed rail, and zero-emission sources of power, too. Andreessen’s critique crystallized something numerous scholars and commentators had been saying, and it had fans across the political spectrum. There was much less agreement on how we’d gotten here, however. Was it cultural malaise? Broken political institutions? Too much regulation? People seemed to agree that the U.S. had lost some essential dynamism, but couldn’t agree why.