The U.S. economy just grew at its fastest quarterly pace ever—but doubts loom about the rest of the year

The economy just experienced its fastest three months of growth in U.S. history.

In the third quarter, from July to September, GDP climbed 33.1% on an annualized basis, according to data released Thursday by the U.S. Bureau of Economic Analysis.

This historic climb follows the U.S. record 31.4% annualized GDP decline in the second quarter and the 5% annualized decline in the first quarter. During that period economists around the world were in a panic and questioning if the...