Let’s start with the Bancroft-winning portrait of Chicago you’ve cited. Nature’s Metropolis shows how cities shape their hinterlands and whole countries.

Nature’s Metropolis tells the story of Chicago’s relationship with the great American hinterland. It certainly shaped my understanding of the role that cities played in the 19th century. William Cronon tells this story through a series of commodities, from the timber of the early forest that came down through Lake Michigan, to the corn of Iowa that produced the pigs that were slaughtered in Chicago and then shipped back east. He tells the story of the triumph of Chicago over the earlier porkopolis Cincinnati, which was due to the fact that Chicago enabled America to access the wealth of the Iowa farmland, which was significantly more productive than the old hinterland of the Ohio River Valley.

He also makes the case that even when cities form for utterly prosaic reasons, like the fact that when the Illinois and Michigan Canal and the Erie Canal were completed, Chicago became the linchpin of a great watery arch that spanned all the way from New York to New Orleans. Even though there are prosaic transportation-cost reasons why Chicago came to be, remarkable things happen when smart people get together in urban areas. He tells the story of the creation of the Chicago Board of Trade – where smart people are innovating because they are next to each other, because they actually see opportunities because they get ideas from each other.

But Cronon also brings to light the darker side of cities, doesn’t he? How cities encouraged the destruction of forests, the displacement of native people and the repackaging of nature’s wealth as paper commodities. What does Cronon say about how cities despoil countries and how do you fit his points into your master thesis?

Cronon was originally a landscape historian. Though it is certainly true that the economic progress of the last century led to enormous changes in uses of the land, I’m not sure that I would lay the blame on cities. Cities certainly enable progress; they were part of that change. And any time we have development there are environmental challenges that must be managed. But people tend to do less damage when they are concentrated on less land. So I tend to think of the options facing America and the world not by comparing urban living to the pre-agrarian existence of Native Americans – I don’t think that’s a viable future even though it would be environmentally sensitive.

Next, the digested discourses of George Washington Plunkitt – a 19th-century New Yorker and a prominent member of the Tammany Hall machine, who held as many as four public offices simultaneously. His rostrum was a shoeshine stand in a downtown courthouse. Tell me about Plunkitt of Tammany Hall and what you drew from William Riordon’s book.

This is sort of a primary source. Plunkitt, a somewhat corrupt politician, unabashedly defends the system he was part of in his own words. It’s a wonderful picture of how [the New York Democratic party organisation] Tammany Hall worked and how New York worked. It’s not filtered through the lens of either later historians or through the lens of progressive muckrakers. His humanity, his life, comes out in the book.

Plunkitt famously made a distinction between honest and dishonest graft. Dishonest graft, explicitly getting paid for some public service or taking from the treasury – was explicitly not allowed, even by Tammany Hall. But honest graft, which is buying up land that he knew would be needed for some public improvement project and then reselling the land to the government at a profit, was OK by him and something he became rich by doing. Voters, ethicists and anyone in government today may not see the distinction as being all that material. But you’ve got to admire his pluck.

Why are the century-old musings of a cynical politician central to understanding cities?

Cities require government. There is a huge externality when you crowd people together in dense urban areas. There are costs associated with crime, disease, infrastructure and traffic congestion. There is a reason why people in New York like government more than people in Montana: they need it more. But because they need government they also reveal the weaknesses of the public sector. This is particularly obvious in the developing world today, where municipal governments are so tragically unable to provide decent services. Tammany Hall is a place that, after [its mid-19th century leader, William] Tweed, seemed to be all right at providing services – although there were a lot of transfers that went along with them to Tammany Hall’s friends. Plunkitt reminded us of how challenging it was for America to come to a place where there was a modicum of honesty in our municipal governments.