Sir Trevor concludes his epic journey through the heartland of the USA following the course of its most famous and important river, the Mississippi. This week he takes the pulse of America today as he travels through the Mid-West States. His first stop is St Louis where he meets one of America's richest baseball teams. On an island in the Mississippi he visits the biggest weapons factory in the USA which has made guns for every conflict the United States has fought in. And in Minneapolis he discovers that the recession hit States isn't affecting business at the enormous Mall of America - the most visited shopping centre in the world. Finally Sir Trevor's in for a surprise as he reaches his ultimate destination, the source of the Mississippi River.