This is from the World Bank, which increasingly seems to be adopting the functions (or at least the methods) of campaigning NGOs and thinktanks. Data are for 2009, in purchasing power parity terms. Countries are in black, cities in green, companies in brown. Largest countries are the US and China (with India at number 4); biggest cities are Tokyo and New York, with notable presence of Latin American megacities (Mexico, Sao Paulo, Buenos Aires); top companies are Royal Dutch Shell and Exxon Mobil (oil still trumps tech, sorry Google).
And yes, of course there’s no obvious reason to equate a company’s turnover with a country’s GDP, but it’s still an interesting indicator of scale. [h/t John Magrath]
Update: Fascinating comment from Peter Chowla, pointing out that a better comparison is between government tax revenue and corporate revenue, and when he crunched the numbers (he didn’t include cities), he got only 29 countries in the top 100 – the rest were corporates. Anyone fancy updating Peter’s numbers (he did this back in 2004/5)?