Armed with his Appleton's Guide, Michael Portillo reaches a milestone on his American journey: the boundary between the northern and southern states, known as the Mason-Dixon line. He discovers the origins of what became for black Americans the border between slavery and freedom, in an 18th-century English dispute over land. On the Wilmington and Western Railroad, Michael meets the passenger train Phoebe Snow, created by the railroads at the turn of the 20th century to reassure passengers that clean burning coal wouldn't make their clothes dirty.

Michael uncovers the explosive history of gunpowder production in Delaware, begun by a Frenchman, whose chateau still stands. He then takes a boat trip up the Susquehanna River following the route taken by one of the first English settlers, John Smith.

Michael Portillo continues his American railroad journey from Philadelphia to Jamestown. Michael arrives in the nation's capital, Washington DC, centre of political power in the world's most powerful country. Steered by his Appleton's Guide of 1879, he admires its fine public buildings, including the largest library in the world, and discovers how the capital was built from scratch after a political compromise between North and South.

At the Bureau of Engraving and Printing, Michael meets the man responsible for engraving the portrait of President Abraham Lincoln on the current five-dollar bill and gets his hands on more money than he has ever held in his life. In the offices of the Washington Post, Michael learns about corruption in the corridors of power and how the newspaper toppled a president. He finishes this leg of his journey in the auditorium of the theatre where, in 1865, President Abraham Lincoln was assassinated.