The coming clash between Barack Obama and John McCain is, the pundits tell us, a struggle between two Americas: liberal and conservative; black and white; young and old. But it is also a confrontation between two very different cities – Obama’s Chicago and McCain’s Phoenix – and their richly opposing political traditions.

As Upton Sinclair so brutally, brilliantly chronicled in The Jungle, Chicago, Illinois – nicknamed the “Windy City” just as much for its politics as the icy blasts tearing off Lake Michigan – has long been a crucible for US socialism. Together with Philadelphia and Baltimore, it was the premier city of organised labour and radical activism in the late 19th century