With so much attention focused on a 2012 convention in Charlotte, it might be easy to overlook a convention going on this week. More than 1,000 planners, advocates, nonprofit leaders and elected officials are in town talking about Smart Growth - how to help U.S. cities and towns grow in ways that are healthier for the environment, residents and municipal bottom lines.

Demography is not as sexy as the Democratic National Convention, of course, but an eye-opening presentation Thursday may presage an even greater challenge for the Charlotte metro region than finding $50 million in private money to pay for the convention.

Arthur Nelson, a planning professor at the University of Utah, described what he calls "The Great Senior Sell-off." From 2010 to 2020 the growth in the share of U.S. households without kids will be 90 percent, he said. "I'm not sure we're prepared for that," Nelson said. In addition, after decades of decline, the number of people in the average U.S. household is rising - an unforeseen change that cuts into demand for new housing. Further, this year the first of the baby boom generation hits 65. When seniors move out of their previous homes, they're more likely to end up in rental and multifamily housing.

The boomers' demographic bubble will mean growing demand for multifamily and rental housing. Projections show that in many states, though thankfully not the Carolinas, there will be fewer available buyers for single-family homes than interested sellers. That points to a worrisome glut of single-family houses.

But can the suburbia-loving Charlotte region meet this projected demand for housing that isn't in the familiar, single-family subdivisions? It will be a challenge, for a couple of reasons. First, not-in-my-back-yard resistance to apartment and condo projects is alive and well. Second, in Charlotte almost all never-before-developed land, including farms, was zoned decades ago for single-family subdivisions.

That encourages developers to avoid the cost and hassle of a rezoning and build single-family neighborhoods instead of the mixed-used and higher-density projects the city is trying to attract. It's suburban growth on auto-pilot.

One reason Charlotte was chosen for the 10th Annual New Partners for Smart Growth conference was the city's nationally praised work linking transit-oriented development to its new light rail line, as well as the city's award-winning new street design guidelines, which aim to create streets hospitable to autos, pedestrians and bicyclists alike. Charlotte has built a national reputation for such policies.

But the city should reel in its incentive for suburban subdivision development. Otherwise that out-of-date policy will continue to undermine the vitality of the in-town areas the city hopes to nurture.