Unemployment rates were higher in September than a year earlier in 371 of the 372 United States metropolitan areas, according to the Bureau of Labor Statistics.

The only metro area that recorded a year-over-year unemployment rate decrease was Houma-Bayou Cane-Thibodaux, La., where joblessness fell 1.4 percentage points from 6.5 percent in September 2008 to 5.1 percent in September 2009 (in seasonally unadjusted terms). It’s hard to get too excited about this improvement, though, given that the area had been hit by a hurricane in September 2008.

The greatest increase in unemployment over the last year was in Detroit-Warren-Livonia, Mich., where joblessness grew 8.4 percentage points to a total rate of 17.3 percent in September 2009. The second-greatest year-over-year increase was in Muskegon-Norton Shores, Mich., where the rate rose 6.8 percentage points, to 16 percent.

In September 2009, the overall highest metropolitan rates of unemployment (again, not seasonally adjusted) were in El Centro, Calif., and Yuma, Ariz., where rates touched 30.1 and 24.2 percent, respectively. These two areas, which both border Mexico, are highly agricultural.

The lowest rate, at 2.9 percent, was in Bismarck, N.D.