America’s economy is poised to roar ahead if only Washington would stop holding it back.Ever since the Great Recession officially ended, the private sector has been adding jobs. What’s kept the economy in low gear and the unemployment rate stubbornly high has been the shrinking of government workforces: cops, teachers and other valuable public employees let go in the face of inadequate tax revenue.Most of these layoffs occurred at the state and local level, but a vigorous federal response could have prevented them.That’s what the federal government should do: when local governments — hemmed in by rigid budget rules and limited borrowing authority — are starved for resources during an economic downturn when their tax revenue falls just when demand for their services grows. When such a crisis occurs only Washington can pick up the slack.Estimates are that the aid to localities included in the 2009 federal recovery act — aka, the “stimulus” — saved 400,000 jobs in both the public and private sector.