Here's a random question: Has the mayor of any major American city ever been elected president? It doesn't seem so. Searching the White House site turns up Grover Cleveland, whom someone put in charge of Buffalo way back in the day, for whatever reason, but that's all I can find. Obviously Hubert Humphrey was the mayor of Minneapolis, but he doesn't count either. Dennis Kucinich, former mayor of Cleveland, definitely doesn't count. Maybe Rudy Giuliani someday, but not now.

This doesn't seem all that surprising: anyone who campaigns for president obviously needs to set out with a relatively broad constituency, and mayors usually have a smaller and less diverse base than governors or senators. Still, this isn't the case in many other nations that elect their presidents nationally. Jacques Chirac was once mayor of Paris. Yuri Luzhkov, mayor of Moscow, practically runs everything Putin doesn't, and could maybe find himself next in line for the presidency—if there is a 'next in line'. Mexico City's mayor, Andres Manuel Lopez Obrador, looks like he'll become president real soon. Iran's new president, Mahmoud Ahmadinejad, used to be mayor of Tehran.

But then again, most nations have only one primary urban center that utterly dominates the rest of the country, so mayors, by extension, are much more powerful people. Paris makes up one-seventh of France's population; Moscow one-fourteenth (but a disproportionate percentage of the wealth); Tehran one-fifth; Mexico City one-sixth. By contrast, New York City comprises less than one-fifteenth of the American population—and unlike Moscow, doesn't have an overwhelming percentage of the wealth—and, unlike in many countries, there is at least one major rival city: Los Angeles. (Other countries with "decentralized" urban seats of power include, perhaps, Canada, Brazil, and China.) Relative to national politics, then, being mayor of New York City doesn't carry nearly as much weight as mayor of Moscow, or Paris, or Tehran, or Mexico City. And yes, this is highly relevant to the pressing issues of the day...