Impact of housing vouchersAfter the Los Angeles riots in 1992 the federal government tried to copy this scheme in other cities. Until recently, the results were considered disappointing. Those who moved out of public housing in crime-ridden places showed lower rates of diabetes than those who remained, and mothers who moved showed an increase in happiness similar to the effects of Prozac, an antidepressant. However, children did no better after moving and their mothers did not get better jobs. In a paper published this month, however, Raj Chetty and colleagues at Harvard re-examined the numbers and found that the children who moved earned considerably more in their 20s. This was true only of children who moved before their 13th birthday: older children saw no benefit later on. More recently, Baltimore lost a public-housing case similar to the one in Chicago and, in 2005, provided vouchers for 7,000 families to move to other parts of Maryland. They are still there, and three-quarters of their children are attending much better schools, says Stefanie Deluca of Johns Hopkins. Yet since giving a golden ticket to every poor black family would cost about $30 billion a year, those stuck in highly segregated places will have to save in order to get out.