In this episode, the History Guys consider the advent of air conditioning, and explore its far-reaching implications on everything from architecture and leisure to demography and politics. They also look at what happened when stoves became widely available in the mid-19th century, and how technology altered Americans' way of life.

In this episode, BackStory takes on big oil! And big trees, big water, big whales.. How have changing energy sources shaped the growth and decline of cities and towns? What are the social costs and benefits of new energy technologies?