Also watching closely are the policy makers of the Federal Reserve, which has begun to reel in its post-recession stimulus. It raised interest rates last month and said it planned to do so twice more this year. But signs of a sluggish economy could affect how quickly the central bank moves.

“This raises the stakes for the April report,” said Joshua Shapiro, chief United States economist at MFR, a research firm. “You need to see things pick up in April, or else March won’t look like aberration.”

The market reaction, in any case, was sanguine, with stocks essentially flat for the day.

Barclays has said it expects the economy to actually slow in the first half of 2017, before rebounding modestly in the second half. “Given this data today, we see downside risk in our already soft expectations for the first half,” Mr. Martin said.

The consensus view on Wall Street is that the economy expanded at an annual rate of 1 percent last quarter, with the pace of growth in the current second quarter rising to 3.5 percent.

The March report represents a snapshot of the economy, not an oil painting. And snow and cold weather in many parts of the country clearly took a toll on the construction sector, which barely grew after gaining a total of more than 90,000 jobs in January and February.

“January and February were abnormally warm, so they were pumped up, and you had some payback in March exacerbated by the harsh weather,” Mr. Shapiro said.