The amount it cost Peter Cosco, slave, to buy his freedom in the year 1792: 100 pounds. Finding the original document of the transaction 215 years later and saving it for posterity: priceless.

So said Allegheny County Recorder of Deeds Valerie McDonald Roberts at a news conference yesterday, as she transferred to the Senator John Heinz History Center a folder full of handwritten documents recording the legal status of Mr. Cosco and 55 other African-American slaves from Allegheny County. Read More