The 10 percent confidence level is the lowest level registered for any institution since Gallup began this poll in 1973, Gallup said.
At 76 percent, Americans said they were most confident in the military.
Small business and the police also ranked high, at 65 percent and 57 percent, with Americans expressing "a great deal" or "quite a lot" of confidence in these institutions, the Princeton, N.J., polling agency said.
Also at the bottom of the list were health maintenance organizations, at 19 percent, and organized labor, at 21 percent.
Confidence in Congress has been at its lowest points for several years, Gallup said. The high point was in 1973, when 42 percent of Americans said they had confidence in Congress.
Results are based on nationwide phone interviews with 1,529 adults conducted June 1-4. The margin of error is 3 percentage points.
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