A week of violence and protests in a town outside St Louis are highlighting how poverty is growing most quickly on the outskirts of America's cities, as suburbs have become home to a majority of the nation's poor. In Ferguson, Missouri, a community of 21,000 where the poverty rate has doubled since 2000, the dynamic has bred animosity over racial segregation and economic inequality. Protests over the police killing of an unarmed black teenager on August 9 have drawn international attention to the St Louis suburb's growing underclass. Such challenges aren't unique to Ferguson, according to a report released in July by Brookings Institution, a Washington, DC think tank. The report found that the poor population is growing twice as fast in US suburbs as in city centres. From Miami to Denver, resurgent downtowns have blossomed even as their recession-weary outskirts struggle with soaring poverty. "We've passed this tipping point and there are now more poor people in the suburbs than the cities," said Elizabeth Kneebone, author of the report and a fellow at the Brookings Metropolitan Policy Programme in Washington. "In those communities, we see things like poorer health outcomes, failing schools and higher crime rates." Ferguson, once a majority white community that's now about two-thirds black, highlights that dynamic. Coinciding with the decline in white population is a rapid rise in poverty since 2000, a period that includes the 18-month recession that ended in June 2009. The St Louis metropolitan area ranked as one of the most segregated in the US in a 2011 study by Brown University in Rhode Island. "Looking at the neighbourhood poverty rates, it's striking how much has changed over a decade," Kneebone said. "In Ferguson in 2000, none of the neighbourhoods had hit that 20 per cent poverty rate. By the end of the 2000s, almost every census tract met or exceeded that poverty rate. That's a really rapid change in a really short time." Suburbs from the outskirts of Atlanta to Colorado Springs have seen similar trends. The number of poor people living in impoverished US suburbs has more than doubled since 2000, compared to a 50 per cent rise in cities. More than half of the 46 million Americans in poverty now lived in suburbs, Kneebone said. Rising suburban poverty was greater in the Midwest, said Lincoln Quillian, professor of sociology at Northwestern University in Evanston, Illinois. The surge of recent foreclosures spurred the upward trend, while urban gentrification displaced poor people to the suburban fringe, he said. There was "more risk" of unrest because of the suburban poverty increase, said Quillian.