1. Tractor Revolution

In the 1870s, harvesting crops is grueling, back-breaking work. Farmers must walk miles behind horse drawn plows to get food on American tables. But a group of dreamers--all of them rivals--has a vision that will change farming forever and create one of the world's most iconic machines: the tractor. Their quest to corner the market--worth 75 billion today--produces some of the greatest innovations and most iconic brands of all time: Caterpillar, John Deere, and Ford.