Our colleagues at The Pew Charitable Trusts, with whom we collaborate on Subsidyscope, have produced a nine-page overview of federal subsidies — the “hidden budget” — that’s worth a read.

The paper is packed with interesting data and useful context. For instance:

*In 2007, the federal government subsidized about $874 billion of the nation’s health care.

*The first known U.S. subsidy — which gave fishermen five cents for every barrel of pickled fish they exported — dates to 1789.

*From 1974 to 2004, the amount of revenue lost to the government due to tax breaks tripled, from $240 billion to $730 billion.

*The biggest tax break — “Exclusion of employer contributions for medical insurance premiums and medical care” — is projected to cost the government $155 billion in fiscal year 2010, which starts tomorrow. The second-biggest — the mortgage-interest deduction — is expected to lop off another $108 billion in revenue.

Keep coming back to Subsidyscope as we unearth stories on little-noticed federal programs and extricate datasets buried in the bowels of federal agencies (in some cases pried loose only with the aid of the Freedom of Information Act). As the Pew people put it in their paper, “We are taking something that is hard to find and making it easy to get. We are turning over rocks and shining a light on what is underneath.”