Inner City Music Photos: Sex and the City — the Business .

One important thing about cities is their sex appeal - their magnetism. Places flourish when they attract people, resources, opportunities, and ideas, and meet them to one another. Cities are much more than the built environment of roads and real estate. Cities are about relationships, and whether people have access to opportunities. Cities are one big dating game.

When cities lose their magnetism, the whole population suffers. The decline of Detroit began well before recent auto industry woes; its population plunge was confirmed by the latest Census. Some attribute decline to bad urban redevelopment schemes or corrupt politics that failed to better schools or reduce crime. "A once-great American city today repels people of talent and ambition," a Wall Street Journal columnist wrote recently. A local leader told him, "It's been class warfare on steroids, and . so many Detroiters who had the means - black and white - have fled the city."

Cleveland is another shrunken city with significant poverty. In the 1980s, Cleveland Tomorrow, a coalition of major company CEOs, sponsored downtown projects, including a new baseball stadium and the Rock and Roll Hall of Fame. This attracted luxury apartment developments, luring the affluent to the center city and revitalizing it. But inner city ghettoes were barely touched, and the country continued to sustain high-wage manufacturing.

There's a narrative of two cities within many city borders: one rich, the other very poor. Dubai, a gleaming new city of luxury high rises, is ringed by hidden slums for temporary service workers from the underclass of Asian nations. In New York, the middle class, including young families, cannot afford to be in the city. Baton Rouge has affluent areas with some of Louisiana's best quality-of-life indicators and extreme poverty areas with some of the worst. Other divides include racial and ethnic enclaves that shift in opportunities - for example, minority entrepreneurs with bright business ideas who can't access mainstream sources of capital and support.

Cities should be connectors but can have connection problems. Cities are where all parts of life come together: jobs, health, education, environmental quality. Yet, in most cities, businesses, schools, hospitals, and city services still operate in silos. And the political boundaries of cities don't encompass their true extent or the light of people, as the Brookings' Metropolitan Policy Center points out. IBM's Smarter Cities Challenge supports efforts to use technology for connected regional solutions.

Interdependence among urban issues makes vicious cycles worse. If there is no action on high youth unemployment or poor educational quality and high school dropout rates, then too many African-American males end up in prison. High crime rates make sections of cities undesirable, and neighborhoods deteriorate. Aging buildings and toxic environments then cause health problems, such as lead poisoning or asthma, which disproportionately affect inner city children. Children in poor health have trouble learning, learning problems are associated with school dropouts, and vicious cycles continue.

Pivotal investments can start virtuous cycles. The version of Miami from sleepy southern city to international trade hub and informal capital of Latin America was propelled by investments in a world class airport and a flood of immigrants from Fidel Castro's Cuba. Mayors and civic leaders took advantage of this to make new businesses and tout Latin connections, as my book World Class describes. But progress stalls if benefits don't reach the grass roots, racial divides persist, and major institutions fail to collaborate. The Miami Foundation's emerging leaders program is designed to deploy diverse younger professionals for major civic projects.

Revitalizing cities requires national urban policy investments and social innovations on the ground. Leadership might be from:

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• Enlightened mayors who build public-private partnerships or join Cities of Service, which coordinate the city and non-profits around high-impact goals.
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• Business leaders, such as former Miami Herald publisher David Lawrence, who rallied Miami-Dade County to vote for a tax increase (Yes to new taxes! to have the Children's Trust, a fund to better living for all children.
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• Faith communities, such as Rev. Raymond Jetson's community organizing toward a coalition for "A Better Baton Rouge."
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• Financiers, such as Tim Ferguson and Ron Walker, who co-founded Next Street to put in inner city businesses.
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• Social entrepreneurs, such as Hubie Jones, who wants to retell a birth-to-college educational model like the Harlem Children's Zone in Boston.
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• Community foundations with a strategic perspective, seeking integrated solutions across issues such as youth employment, education, health, and green plans.
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The best social innovations will connect people and institutions, producing an infrastructure for collaboration. That social infrastructure will make the sex appeal of cities by going beyond initial attraction to have lasting relationships for lasting improvements.