While the 2008 presidential campaign is in full swing, Simon Schama travels through America to dig deep into the conflicts of its history to understand what is at stake right now. Simon looks at the bitter conflict over immigration in American history. Who should be allowed to enter America and call themselves an American has always been one of the nation's most divisive issues, and it continues to be so at this election. He traces the roots of this conflict to the founding of America. The early settlers were themselves immigrants, but they saw America as fundamentally a white and Protestant nation. Simon looks at the key events that challenged this view: the annexation of parts of Mexico in 1848 that made 100,000 non-whites American citizens, the immigration and subsequent expulsion of the Chinese in the late 19th century, and the massive immigration from Eastern Europe during the industrialisation of the 1920s. Each time there have been those who have insisted America must stay white if it's to stay true to itself, and each time they have been defeated by the sheer force of history. John F Kennedy defined America as a Nation of Immigrants in 1964 and Simon argues that the candidacy of Barack Obama represents the final triumph of the vision of America as a multi-ethnic nation.