The U.S. economy is projected to grow at a robust 4.6% annual rate this year, but employment isn't expected to return to pre-pandemic levels until 2024, the Congressional Budget Office said Monday.

The 10-year outlook said the economic recovery from the coronavirus got a boost from an unprecedented wave of government spending to combat the outbreak, such that growth could pass its maximum sustainable level in early 2025 before returning to a long-run average of 1.7%. Based on the CBO's projections, economic growth would be the strongest since 1999.

While the growth estimates suggest a quick sn...