Metropolitan Boston exhibited the second highest level of online managerial hiring in the country in May, according to The CareerCast.com/JobSerf Employment Index.

Boston’s managerial hiring index rose eight points this month compared to last year, to 131. Washington, D.C. was tops in the nation with an index of 172, 10 points higher than May of 2009. San Francisco rounded out the top three, with a score of 106, up eight points from last year.

May marked the first time three cities have been over the 100 benchmark since the survey’s inception, according to a statement.

Despite the strength in the leading three markets, however, the nationwide managerial hiring index fell 3.3 points from April, to 89. It was the first monthly retreat for the index in 2010, after beginning the year at 70.8, the companies said.

"Even though hiring levels this month are more than 30 points above May 2009 (89 vs. 56.6), we still need to see a significant improvement in managerial hiring before we will see a reduction in the overall unemployment rate," said Tony Lee, publisher of CareerCast.com.

The Midwest continues to suffer in hiring, with Indianapolis (down 4 to 47), St. Louis (down 3 to 42) and Cincinnati (down 3 to 40) all down considerably. Declines in the South were also reflected in Nashville’s hiring activity, which dropped 3 points to 50.

Detroit, where hiring activity rose 11 percent for an index reading of 30, and Riverside, up 12 percent to 19, topped the list of highest percentage improvements in per capita hiring, although they still came in at the bottom of the rankings.