It’s dangerous to express optimism about the economy these days. Europe’s financial markets remain fragile. China, which supports much of the world’s economy through imports, is too dependent on highly indebted, state-subsidized corporations. The Federal Reserve may reverse its low-interest-rate policy. Nevertheless, there is at last some fundamentally positive economic news to be reported: the United States may be on the verge of GDP growth rapid enough to bring down the unemployment rate substantially.

The nation’s debt as a percentage of GDP has stabilized and is forecast to begin falling in 2015, while consumer debt has already dropped significantly…