In 2006 Alaskan senator Ted Stevens described the Internet as a “series of tubes,” a quip that earned the octogenarian widespread mockery. But as Blum notes in his charming look at the physical infrastructure that underlies the Web, Stevens wasn’t all that wrong. Bits sail through a worldwide network of fiber-optic cables and come together in junctions where Internet providers connect their pipes to the networks of others. Blum’s transcontinental journey exposes some of the important issues confronting the Internet, such as the occasional disconnect between the interests of the corporations who control the physical pipes and the good of the network as a whole. “If you believe the Internet is magic,” he writes, “then it’s hard to grasp its physical reality.” I’d turn this around: only by understanding the physical richness of the Internet can we truly grok the thorny forces that are shaping its growth.