The economic recovery is proceeding unevenly in its early stages, with areas hurt most by the housing slump still lagging behind other regions, according to The Associated Press' monthly analysis of economic stress in more than 3,100 U.S. counties.

Counties in the Southeast, the industrial Midwest and the Southwest are still struggling and have made the least improvement, the analysis of September data found. The northern half of the nation is stabilizing or improving faster than the southern half. Northern counties generally didn't suffer as much from the housing bust.

The government said last week that the U.S. economy grew at a 3.5 percent annual rate in the third quarter, ending four straight quarters of decline. But that growth is expected to slow as government stimulus programs wind down.

The AP's Economic Stress Index calculates a score from 1 to 100 based on a county's unemployment, foreclosure and bankruptcy rates. Under a rough rule of thumb, a county is considered stressed when its score exceeds 11.

Nationwide, the average county's Stress score dipped to 10.1 in September from 10.3 in August, helped by a steadying of foreclosure and bankruptcy rates. In September 2008, the average county Stress score was much lower: 6.73.

The highest Stress scores were still found mainly in states that endured housing booms and busts. Nevada had the highest score, 21.95, followed by Michigan, with its battered auto industry, at 17.75. California was next, at 16.2, followed by Florida, 15.4, and Arizona, 14.26.

States with the lowest Stress scores in September were North Dakota (4.07), South Dakota (5.01), Nebraska (5.71), Montana (6.6) and Wyoming (6.9).

"Housing still is at the epicenter of this crisis around the country, and places where the cycle was most egregious are also now places that are seeing some of the highest rates of unemployment," said Sean Snaith, an economist at the University of Central Florida.

Midwestern and Plains states such as Oklahoma, Nebraska, North Dakota and Iowa avoided the worst of the housing and financial crises. And Oklahoma and North Dakota have recently benefited from rising oil prices. The region also has been helped by a weaker dollar, which has made agricultural commodities cheaper for foreigners to buy.

Areas of the Northeast, such as Pennsylvania and upstate New York, are benefiting from economically stable industries like higher education and health care. Those are the two industries that have added jobs during the recession.

Pittsburgh, for example, is no longer an old-line industrial city.