The economic performance of cities: Following the sun AMERICA'S crisis owes something to baby-boomers" taste for sun. From the 1970s the share of Americans living in the southern half of the country climbed steadily, from under 40% to more than half by the 2000s. Climate helped motivate the shift (as climate control helped populate the Deep South, almost uninhabitably humid before air-conditioning). Economic opportunity also exerted a strong pull. This flow provided the underlying energy for America's housing boom and bust. Recently released figures on metropolitan-area GDP, adjusted for inflation, reveal the sunbelt's multitudes. San Jose, California - home of Silicon Valley - enjoyed GDP growth of an impressive 19% from 2007 to 2011, while the economy of Austin, the capital of Texas, expanded by 14%. The laggards, though, are similarly sun-drenched. The GDP of Las Vegas shrank 12% from 2007 to 2011. It was joined down at the bottom by Los Angeles, Miami, Phoenix and Atlanta. Employment figures tell a very similar story. Since the beginning of the recession (and to the end of March 2013) Texas has accounted for four of the metropolitan areas with the biggest rise in employment, alongside Nashville, Tennessee and Oklahoma City, Oklahoma. But other sunny cities are also among those which have lost most ground on jobs. Los Angeles remains some 300,000 jobs short of its pre-recession peak, about 5.3% of total employment. Housing explains much of this variation. Migration, driven by sun and economic growth, fuelled a voracious demand for new homes across the sunbelt. House prices soared in places like coastal California, where a scarcity of usable land and tight regulations on new construction have limited building. Lax lending standards encouraged reckless borrowing - except in Texas, where strict rules on predatory lending imposed after an earlier bust kept mortgages modest. In contrast to California, builder-friendly cities like Dallas and Houston added huge amounts of new housing, allowing them to accommodate crowds of new residents without causing much upward pressure on prices. From 2000 to 2007 house values rose by 20-30% in Denver, Atlanta and Dallas, according to the S&P/Case-Shiller index. But prices soared 90% in Phoenix and Las Vegas, and more than doubled in Los Angeles and Miami (as well as in Washington, DC, and New York). When mortgage markets froze in 2008 and the economy sank into deep recession, metropolitan areas with high concentrations of weak borrowers fared the worst. The sunbelt's excessive downswing now looks as though it may have bottomed out. Since late 2011, rapid employment growth has again spread across the sunbelt (see chart). Previously depressed places like Phoenix and Atlanta are outpacing cities that did better earlier in the recovery, such as Boston and Minneapolis. The sunbelt gap is starting to close again as the recovery continues. That is partly the result of rapid household deleveraging. Foreclosures came fast and furious in California and Florida. This contributed to a deep economic swoon, but it also helped borrowers escape crushing debts. A return to affordability has also helped. By 2011 house values in Washington, DC, were still 79% above their level in 2000, and prices in New York and Boston were 63% and 49% higher. In San Francisco prices were just 29% higher, however. Prices in Phoenix fell to 2000 levels, and Atlanta prices sank 11% below them. America's southward migration has duly resumed, providing new buyers for local houses and new demand for local businesses. Industry matters, too. The fortunes of Texas, like Oklahoma's and Louisiana's, have been buoyed by high energy prices. California's recent better times owe much to a renewed tech boom, which has also been good for smaller tech centres like Austin, and even for Portland, Oregon (firmly in the north). But America's economic growth since 2007 is mostly population-driven. Outside a few highly skilled tech cities, rises in output per person contributed little to GDP. Instead, output and jobs are following the people, and the people are again following the sun.