All the candidate cities face this problem.

ECONOMIST: Britain's Olympic bid

The city was ranked down in fourth when the International Olympic Committee examined the five candidate cities' plans last May.

BBC: Olympic X - most sports on two intersecting transport axes

Thursday marks the deadline for a clutch of candidate cities to host the 2016 games, but with London's bill to host the 2012 Olympics growing to eye-watering heights, one wonders if the enthusiasm from Chicago, Tokyo, Rio de Janeiro and Madrid will be tempered by the economic downturn.

FORBES: Magazine Article

To determine the rankings, we started with a list of the largest metropolitan areas in the continental U.S. Thirty-five candidate cities were chosen based on availability of data and geographic diversity.

FORBES: America's Drunkest Cities

Even in the Republican CNN-YouTube debate, GOP candidate Mitt Romney said fathers are part of the answer to addressing crime in inner cities.

CNN: Commentary: Black men must reclaim our children

Among high-income world cities, London might finally reach 10 million while the only other high-income world candidate, Chicago, with more than 9 million residents, could take until 2040.

FORBES: The World's Fastest-Growing Megacities